Knowledge (XXG)

Triangular number

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837: 2411: 2405: 3604: 126: 3664: 3652: 1596: 20: 6791: 4947: 35: 2395: 2689: 7100: 9034: 2063: 1414: 423: 1108: 4937: 2390:{\displaystyle T_{n}+T_{n-1}=\left({\frac {n^{2}}{2}}+{\frac {n}{2}}\right)+\left({\frac {\left(n-1\right)^{2}}{2}}+{\frac {n-1{\vphantom {\left(n-1\right)^{2}}}}{2}}\right)=\left({\frac {n^{2}}{2}}+{\frac {n}{2}}\right)+\left({\frac {n^{2}}{2}}-{\frac {n}{2}}\right)=n^{2}=(T_{n}-T_{n-1})^{2}.} 3599: 208: 590:, imagine a "half-rectangle" arrangement of objects corresponding to the triangular number, as in the figure below. Copying this arrangement and rotating it to create a rectangular figure doubles the number of objects, producing a rectangle with dimensions 4218: 5201:", describing them as "deeply intuitive" and "featured in an enormous number of games, incredibly versatile at providing escalating rewards for larger sets without overly incentivizing specialization to the exclusion of all other strategies". 2980: 3370: 3361: 2059:
Most simply, the sum of two consecutive triangular numbers is a square number, with the sum being the square of the difference between the two (and thus the difference of the two being the square root of the sum). Algebraically,
1409:{\displaystyle {\begin{aligned}\sum _{k=1}^{m}k+(m+1)&={\frac {m(m+1)}{2}}+m+1\\&={\frac {m(m+1)+2m+2}{2}}\\&={\frac {m^{2}+m+2m+2}{2}}\\&={\frac {m^{2}+3m+2}{2}}\\&={\frac {(m+1)(m+2)}{2}},\end{aligned}}} 4837: 1968: 4477:". This theorem does not imply that the triangular numbers are different (as in the case of 20 = 10 + 10 + 0), nor that a solution with exactly three nonzero triangular numbers must exist. This is a special case of the 969: 2047: 2817: 3794: 3221: 4735: 4653: 5013:. For example, a group stage with 4 teams requires 6 matches, and a group stage with 8 teams requires 28 matches. This is also equivalent to the handshake problem and fully connected network problems. 4295: 1075: 4095: 2503: 1113: 214: 3815:
The final digit of a triangular number is 0, 1, 3, 5, 6, or 8, and thus such numbers never end in 2, 4, 7, or 9. A final 3 must be preceded by a 0 or 5; a final 8 must be preceded by a 2 or 7.
4456: 418:{\displaystyle \displaystyle {\begin{aligned}T_{n}&=\sum _{k=1}^{n}k=1+2+\dotsb +n\\&={\frac {n^{2}+n{\vphantom {(n+1)}}}{2}}={\frac {n(n+1)}{2}}\\&={n+1 \choose 2}\end{aligned}}} 5527: 832: 1791: 474: 3651: 2618: 683: 2838: 6982: 4365: 7136: 4826: 3101: 769: 4571: 626: 104:
0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105, 120, 136, 153, 171, 190, 210, 231, 253, 276, 300, 325, 351, 378, 406, 435, 465, 496, 528, 561, 595, 630, 666...
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The converse of the statement above is, however, not always true. For example, the digital root of 12, which is not a triangular number, is 3 and divisible by three.
2651: 6972: 4766: 1812: 628:, which is also the number of objects in the rectangle. Clearly, the triangular number itself is always exactly half of the number of objects in such a figure, or: 710: 588: 6625: 1462: 1101: 871: 3226: 1979: 1542: 1522: 1502: 1482: 1436: 991: 864: 514: 3826:
of a nonzero triangular number is always 1, 3, 6, or 9. Hence, every triangular number is either divisible by three or has a remainder of 1 when divided by 9:
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A square whose side length is a triangular number can be partitioned into squares and half-squares whose areas add to cubes. This shows that the square of the
836: 7065: 2727: 1578:. However, regardless of the truth of this story, Gauss was not the first to discover this formula, and some find it likely that its origin goes back to the 2427:
There are infinitely many triangular numbers that are also square numbers; e.g., 1, 36, 1225. Some of them can be generated by a simple recursive formula:
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Ross, H.E. & Knott, B.I."Dicuil (9th century) on triangular and square numbers." British Journal for the History of Mathematics, 2019,34 (2), 79-94.
4932:{\displaystyle {\begin{array}{ccccccc}&4&3&2&1&\\+&1&2&3&4&5\\\hline &5&5&5&5&5\end{array}}} 3692: 3812:
For example, the third triangular number is (3 × 2 =) 6, the seventh is (7 × 4 =) 28, the 31st is (31 × 16 =) 496, and the 127th is (127 × 64 =) 8128.
114: 3594:{\displaystyle \sum _{n_{k-1}=1}^{n_{k}}\sum _{n_{k-2}=1}^{n_{k-1}}\dots \sum _{n_{2}=1}^{n_{3}}\sum _{n_{1}=1}^{n_{2}}n_{1}={\binom {n_{k}+k-1}{k}}} 3029:(66) equals the fifth triangular number, 15. Every other triangular number is a hexagonal number. Knowing the triangular numbers, one can reckon any 7129: 5734:
Esposito, M. An unpublished astronomical treatise by the Irish monk Dicuil. Proceedings of the Royal Irish Academy, XXXVI C. Dublin, 1907, 378-446.
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designers Geoffrey Engelstein and Isaac Shalev describe triangular numbers as having achieved "nearly the status of a mantra or koan among
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The number of line segments between closest pairs of dots in the triangle can be represented in terms of the number of dots or with a
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In 1796, Gauss discovered that every positive integer is representable as a sum of three triangular numbers (possibly including
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The digital root pattern for triangular numbers, repeating every nine terms, as shown above, is "1, 3, 6, 1, 6, 3, 1, 9, 9".
8725: 4493: 4302: 2410: 2404: 7075: 6977: 6611: 6184: 3948:, which yields all the odd squares are revealed by multiplying a triangular number by 8 and adding 1, and the process for 8041: 9073: 8391: 7710: 7503: 7103: 6438: 5880:
Liu, Zhi-Guo (2003-12-01). "An Identity of Ramanujan and the Representation of Integers as Sums of Triangular Numbers".
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both of which can easily be established either by looking at dot patterns (see above) or with some simple algebra.
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This fact can be demonstrated graphically by positioning the triangles in opposite directions to create a square:
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th triangular number. However, although some other sources use this name and notation, they are not in wide use.
3030: 2709: 430: 9088: 7629: 5608: 4518: 4213:{\displaystyle \sum _{n=1}^{\infty }{1 \over {{n^{2}+n} \over 2}}=2\sum _{n=1}^{\infty }{1 \over {n^{2}+n}}=2.} 2543: 631: 7886: 6228: 8755: 8720: 8506: 8416: 8290: 8265: 8174: 8164: 7776: 7758: 7678: 7052: 6874: 6504: 6481: 6406: 4967: 4499: 9015: 8285: 8159: 7790: 7566: 7346: 7273: 6714: 6661: 6518: 6299: 4089: 3641: 843: 4507: 8270: 8124: 8051: 7206: 6921: 6666: 6573: 6098: 5691: 4503: 3627:, and its diagonals being simplex numbers; similarly, the fifth triangular number (15) equals the third 8979: 8619: 6174: 4778: 5611:, a triangular number whose position in the sequence of triangular numbers is also a triangular number 3960:
is an odd square is the inverse of this operation. The first several pairs of this form (not counting
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people shakes hands once with each person. In other words, the solution to the handshake problem of
8634: 8498: 8493: 8461: 8224: 8199: 8194: 8169: 8099: 8095: 8026: 7916: 7748: 7544: 7513: 7012: 6879: 6471: 6277: 6102: 4530: 3674: 1973: 1806: 1599: 593: 560: 125: 9033: 1595: 9083: 9037: 8791: 8786: 8700: 8674: 8572: 8551: 8323: 8204: 8154: 8076: 8046: 7986: 7753: 7733: 7664: 7377: 6853: 6838: 6810: 6790: 6729: 6499: 6476: 6392: 6154: 6073: 5965: 5924: 5905: 5840: 4223: 3115: 2975:{\displaystyle \sum _{k=1}^{n}T_{k}=\sum _{k=1}^{n}{\frac {k(k+1)}{2}}={\frac {n(n+1)(n+2)}{6}}.} 2832: 157: 7921: 6942: 5713: 5105:
the current year in the depreciation schedule. Under this method, an item with a usable life of
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Formulas involving expressing an integer as the sum of triangular numbers are connected to
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Sun, Zhi-Hong (2016-01-24). "Ramanujan's theta functions and sums of triangular numbers".
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cables or other connections; this is equivalent to the handshake problem mentioned above.
4772: 3356:{\displaystyle \sum _{n_{2}=1}^{n_{3}}\sum _{n_{1}=1}^{n_{2}}n_{1}={\binom {n_{3}+2}{3}},} 55: 5893: 1441: 1080: 1602:
that the number of possible handshakes between n people is the (n−1)th triangular number
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Fang: Nonexistence of a geometric progression that contains four triangular numbers
5575: 5021: 5017: 3823: 1674: 1579: 4962:-th triangular number plus one, forming the lazy caterer's sequence (OEIS A000124) 2416:
The double of a triangular number, as in the visual proof from the above section
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Alternating triangular numbers (1, 6, 15, 28, ...) are also hexagonal numbers.
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Triangular numbers have a wide variety of relations to other figurate numbers.
1963:{\displaystyle L_{n}=3T_{n-1}=3{n \choose 2};~~~L_{n}=L_{n-1}+3(n-1),~L_{1}=0.} 9003: 8984: 8280: 7891: 6140: 5194: 4502:
posed the question as to the existence of four distinct triangular numbers in
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th triangular number is the number of dots in the triangular arrangement with
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is the length in years of the asset's useful life. Each year, the item loses
1551:, is said to have found this relationship in his early youth, by multiplying 8609: 8536: 8528: 8333: 8247: 7365: 6686: 6558: 6219: 5614: 5579: 4829: 1653: 964:{\displaystyle T_{1}=\sum _{k=1}^{1}k={\frac {1(1+1)}{2}}={\frac {2}{2}}=1.} 195: 185: 175: 98: 6049: 6059: 2042:{\displaystyle \lim _{n\to \infty }{\frac {T_{n}}{L_{n}}}={\frac {1}{3}}.} 8710: 6634: 5617:, an arrangement of ten points in a triangle, important in Pythagoreanism 1587: 1582:
in the 5th century BC. The two formulas were described by the Irish monk
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The sum of two consecutive triangular numbers is a square number since:
3607:
The fourth triangular number equals the third tetrahedral number as the
8715: 8374: 6603: 6024: 5969: 3819: 2812:{\displaystyle \sum _{k=1}^{n}k^{3}=\left(\sum _{k=1}^{n}k\right)^{2}.} 480:. It represents the number of distinct pairs that can be selected from 5765: 6016:
Algebra in Context: Introductory Algebra from Origins to Applications
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The triangular numbers are given by the following explicit formulas:
5961: 6238: 5929: 5758:"The Handshake Problem | National Association of Math Circles" 5661:(4th ed.). Houston, Texas: Publish or Perish. pp. 21–22. 1621:
of counting the number of handshakes if each person in a room with
6107:, vol. 1 (2nd ed.), J. Johnson and Co., pp. 332–335 5945: 4945: 4775:, is visually demonstrated in the following sum, which represents 3789:{\displaystyle M_{p}2^{p-1}={\frac {M_{p}(M_{p}+1)}{2}}=T_{M_{p}}} 3602: 3216:{\displaystyle \sum _{n_{1}=1}^{n_{2}}n_{1}={\binom {n_{2}+1}{2}}} 2687: 1594: 33: 18: 6119:
The Art of Computer Programming: Volume 1: Fundamental Algorithms
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to be impossible and was later proven by Fang and Chen in 2007.
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Relationship between the maximum number of pips on an end of a
4730:{\displaystyle ={\frac {1}{2}}\,n{\Bigl (}(n-1)+(n+1){\Bigr )}} 1976:, the ratio between the two numbers, dots and line segments is 4648:{\displaystyle ={\frac {1}{2}}\,n(n-1)+{\frac {1}{2}}\,n(n+1)} 5714:"Webpage cites AN INTRODUCTION TO THE HISTORY OF MATHEMATICS" 5550:
is a square. Equivalently, if the positive triangular root
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is triangular (as well as hexagonal), given by the formula
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that all hexagonal numbers are odd-sided triangular numbers
1590:. An English translation of Dicuil's account is available. 109: 4290:{\displaystyle \sum _{n=1}^{\infty }{1 \over {n(n+1)}}=1.} 3640:
Triangular numbers correspond to the first-degree case of
1070:{\displaystyle T_{m}=\sum _{k=1}^{m}k={\frac {m(m+1)}{2}}} 2718:
is the same as the sum of the cubes of the integers 1 to
6235:, some higher dimensions, and some approximate formulas 5858:
Chen, Fang: Triangular numbers in geometric progression
4995:, the number of matches that need to be played between 3114:
The positive difference of two triangular numbers is a
1571:
pairs of numbers in the sum by the values of each pair
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Derivation of triangular numbers from a left-justified
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is the item's beginning value (in units of currency),
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th triangular number is equal to the sum of the first
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1/2 + 1/3 + 1/5 + 1/7 + 1/11 + ⋯ (inverses of primes)
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1 − 1 + 2 − 6 + 24 − 120 + ⋯ (alternating factorials)
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is the total number of years the item is usable, and
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Shell-Gellasch, Amy; Thoo, John (October 15, 2015).
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in the fourth, accumulating a total depreciation of
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This property, colloquially known as the theorem of
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Two other formulas regarding triangular numbers are
23:
The first six triangular numbers (not starting with
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There exist triangular numbers that are also square
5450:, one can define the (positive) triangular root of 2498:{\displaystyle S_{n+1}=4S_{n}\left(8S_{n}+1\right)} 2408:    10 + 15 = 25     6048:Engelstein, Geoffrey; Shalev, Isaac (2019-06-25). 5521: 4931: 4820: 4760: 4729: 4647: 4565: 4450: 4359: 4289: 4212: 3788: 3593: 3355: 3215: 3095: 2974: 2811: 2678: 2645: 2612: 2530: 2497: 2389: 2041: 1962: 1785: 1536: 1516: 1496: 1476: 1456: 1430: 1408: 1095: 1069: 985: 963: 858: 826: 763: 704: 677: 620: 582: 551: 508: 468: 417: 78:dots on each side, and is equal to the sum of the 5438:Triangular roots and tests for triangular numbers 4722: 4682: 4451:{\displaystyle T_{ab}=T_{a}T_{b}+T_{a-1}T_{b-1},} 3585: 3551: 3367:, can be generalized. This leads to the formula: 3344: 3316: 3207: 3179: 1870: 1857: 404: 383: 6231:by Rob Hubbard, including the generalisation to 1984: 6121:. 3rd Ed. Addison Wesley Longman, U.S.A. p. 48. 6019:. Johns Hopkins University Press. p. 210. 5522:{\displaystyle n={\frac {{\sqrt {8x+1}}-1}{2}}} 4991:In a tournament format that uses a round-robin 4470:= 0), writing in his diary his famous words, " 4222:This can be shown by using the basic sum of a 7130: 6619: 6254: 6089: 6087: 5745:https://doi.org/10.1080/26375451.2019.1598687 4506:. It was conjectured by Polish mathematician 3021:th triangular number. For example, the sixth 459: 438: 8: 7066:Hypergeometric function of a matrix argument 3931:will always be a triangular number, because 827:{\displaystyle T_{4}={\frac {4(4+1)}{2}}=10} 6922:1 + 1/2 + 1/3 + ... (Riemann zeta function) 5574:As stated, an alternative name proposed by 4976:computing devices requires the presence of 2984:More generally, the difference between the 1786:{\displaystyle 10?=1+2+3+4+5+6+7+8+9+10=55} 8998: 8962: 8926: 8890: 8850: 8524: 8489: 8475: 8364: 8107: 8090: 8005: 7960: 7837: 7795: 7683: 7549: 7540: 7527: 7474: 7431:Possessing a specific set of other numbers 7426: 7360: 7312: 7250: 7154: 7137: 7123: 7115: 6896: 6828: 6651: 6626: 6612: 6604: 6563: 6523: 6411: 6282: 6261: 6247: 6239: 5127:of its "losable" value in the first year, 4484:The largest triangular number of the form 3662: 842:This formula can be proven formally using 469:{\displaystyle \textstyle {n+1 \choose 2}} 6978:1 + 1/2 + 1/3 + 1/4 + ⋯ (harmonic series) 5928: 5791:. Vol. 1 (3rd ed.). p. 48. 5491: 5488: 5480: 4841: 4839: 4812: 4799: 4786: 4780: 4752: 4743: 4721: 4720: 4681: 4680: 4676: 4666: 4661: 4626: 4616: 4594: 4584: 4579: 4557: 4538: 4532: 4433: 4417: 4404: 4394: 4378: 4372: 4342: 4329: 4310: 4304: 4259: 4254: 4248: 4237: 4231: 4189: 4184: 4179: 4173: 4162: 4132: 4127: 4125: 4120: 4114: 4103: 4097: 4092:of all the nonzero triangular numbers is 3778: 3773: 3745: 3732: 3725: 3710: 3700: 3694: 3584: 3561: 3550: 3548: 3539: 3527: 3522: 3509: 3504: 3492: 3487: 3474: 3469: 3448: 3443: 3424: 3419: 3407: 3402: 3383: 3378: 3372: 3343: 3326: 3315: 3313: 3304: 3292: 3287: 3274: 3269: 3257: 3252: 3239: 3234: 3228: 3206: 3189: 3178: 3176: 3167: 3155: 3150: 3137: 3132: 3126: 3121:The pattern found for triangular numbers 3075: 3059: 3050: 3045:-gonal number is obtained by the formula 2927: 2897: 2891: 2880: 2867: 2857: 2846: 2840: 2800: 2786: 2775: 2756: 2746: 2735: 2729: 2664: 2658: 2631: 2625: 2613:{\displaystyle S_{n}=34S_{n-1}-S_{n-2}+2} 2592: 2573: 2557: 2551: 2516: 2510: 2478: 2460: 2438: 2432: 2378: 2362: 2349: 2333: 2311: 2297: 2291: 2268: 2254: 2248: 2219: 2196: 2195: 2183: 2169: 2147: 2124: 2110: 2104: 2084: 2071: 2065: 2026: 2015: 2005: 1999: 1987: 1981: 1948: 1905: 1892: 1869: 1856: 1854: 1836: 1820: 1814: 1709: 1529: 1509: 1489: 1469: 1443: 1423: 1360: 1323: 1316: 1273: 1266: 1214: 1165: 1131: 1120: 1112: 1110: 1082: 1040: 1028: 1017: 1004: 998: 978: 973:Now assume that, for some natural number 945: 915: 903: 892: 879: 873: 851: 791: 782: 776: 728: 719: 696: 690: 678:{\displaystyle T_{n}={\frac {n(n+1)}{2}}} 648: 639: 633: 595: 574: 568: 541: 521: 501: 458: 437: 435: 432: 403: 382: 380: 343: 312: 311: 299: 292: 249: 238: 221: 213: 210: 97:of triangular numbers, starting with the 5946:"Triangular Numbers and Perfect Squares" 5802:Baumann, Michael Heinrich (2018-12-12). 5203: 5001:teams is equal to the triangular number 1547:The German mathematician and scientist, 124: 6051:Building Blocks of Tabletop Game Design 5626: 3623:-simplex number due to the symmetry of 4360:{\displaystyle T_{a+b}=T_{a}+T_{b}+ab} 1669:This same function was coined as the " 6133:Algorithms for Functional Programming 5209:and the number of dominoes in its set 1524:, and ultimately all natural numbers 7: 5944:Beldon, Tom; Gardiner, Tony (2002). 1795:which of course, corresponds to the 6943:1 − 1 + 1 − 1 + ⋯ (Grandi's series) 5690:. Computing Science. Archived from 5531:which follows immediately from the 3894:is also a triangular number, given 2052:Relations to other figurate numbers 1687:(analog for the factorial notation 54:. Triangular numbers are a type of 5894:10.1023/B:RAMA.0000012425.42327.ae 5582:, is "termial", with the notation 5191:(the whole) of the losable value. 4249: 4174: 4115: 3555: 3320: 3183: 1994: 1861: 487:objects, and it is read aloud as " 442: 387: 14: 7061:Generalized hypergeometric series 5810:-dimensionale Champagnerpyramide" 4821:{\displaystyle T_{4}+T_{5}=5^{2}} 3096:{\displaystyle Ck_{n}=kT_{n-1}+1} 771:(green plus yellow) implies that 9032: 8640:Perfect digit-to-digit invariant 7099: 7098: 7071:Lauricella hypergeometric series 6789: 6229:Hypertetrahedral Polytopic Roots 3650: 2724:. This can also be expressed as 2409: 2403: 835: 764:{\displaystyle 2T_{4}=4(4+1)=20} 7081:Riemann's differential equation 5789:The Art of Computer Programming 4479:Fermat polygonal number theorem 2402:6 + 10 = 16     1679:The Art of Computer Programming 1464:. Since it is clearly true for 5817:Mathematische Semesterberichte 4950:The maximum number of pieces, 4717: 4705: 4699: 4687: 4642: 4630: 4610: 4598: 4275: 4263: 3757: 3738: 2960: 2948: 2945: 2933: 2915: 2903: 2375: 2342: 1991: 1935: 1923: 1652:is the additive analog of the 1418:so if the formula is true for 1390: 1378: 1375: 1363: 1232: 1220: 1183: 1171: 1155: 1143: 1058: 1046: 933: 921: 809: 797: 752: 740: 666: 654: 615: 603: 563:. For every triangular number 538: 526: 361: 349: 327: 315: 50:counts objects arranged in an 1: 9064:Factorial and binomial topics 7479:Expressible via specific sums 7076:Modular hypergeometric series 6917:1/4 + 1/16 + 1/64 + 1/256 + ⋯ 6439:Centered dodecahedral numbers 4566:{\displaystyle T_{n-1}+T_{n}} 3884:is a triangular number, then 2546:are found from the recursion 621:{\displaystyle n\times (n+1)} 6444:Centered icosahedral numbers 6424:Centered tetrahedral numbers 5635:"Triangular Number Sequence" 5211:(values in bold are common) 5093:is its final salvage value, 4500:Wacław Franciszek Sierpiński 3223:and for tetrahedral numbers 2417: 2197: 516:th triangular number equals 313: 8568:Multiplicative digital root 7086:Theta hypergeometric series 6434:Centered octahedral numbers 6315:Centered heptagonal numbers 6305:Centered pentagonal numbers 6295:Centered triangular numbers 6180:Encyclopedia of Mathematics 5022:sum-of-years' digits method 5016:One way of calculating the 3615:-simplex number equals the 1660:of integers from 1 to  1484:, it is therefore true for 834:(green).    559:can be illustrated using a 9105: 6968:Infinite arithmetic series 6912:1/2 + 1/4 + 1/8 + 1/16 + ⋯ 6907:1/2 − 1/4 + 1/8 − 1/16 + ⋯ 6539:Squared triangular numbers 6330:Centered decagonal numbers 6325:Centered nonagonal numbers 6320:Centered octagonal numbers 6310:Centered hexagonal numbers 6131:Stone, John David (2018), 5829:10.1007/s00591-018-00236-x 5684:"Gauss's Day of Reckoning" 2825:triangular numbers is the 9028: 9011: 8997: 8975: 8961: 8939: 8925: 8903: 8889: 8862: 8849: 8645:Perfect digital invariant 8488: 8474: 8382: 8363: 8220:Superior highly composite 8106: 8089: 8017: 8004: 7972: 7959: 7847: 7836: 7539: 7526: 7484: 7473: 7436: 7425: 7373: 7359: 7322: 7311: 7264: 7249: 7167: 7153: 7094: 6787: 6141:10.1007/978-3-662-57970-1 6135:, Springer, p. 282, 6117:Donald E. Knuth (1997). 5024:, which involves finding 4494:Ramanujan–Nagell equation 3031:centered polygonal number 2544:square triangular numbers 846:. It is clearly true for 9079:Squares in number theory 8258:Euler's totient function 8042:Euler–Jacobi pseudoprime 7317:Other polynomial numbers 6505:Square pyramidal numbers 6482:Stella octangula numbers 5950:The Mathematical Gazette 5609:Doubly triangular number 4519:Ramanujan theta function 3111:is a triangular number. 2679:{\displaystyle S_{1}=1.} 2531:{\displaystyle S_{1}=1.} 552:{\displaystyle n(n+1)/2} 8072:Somer–Lucas pseudoprime 8062:Lucas–Carmichael number 7897:Lazy caterer's sequence 6799:Properties of sequences 6300:Centered square numbers 4968:fully connected network 4033:, these formulas yield 2646:{\displaystyle S_{0}=0} 1798:tenth triangular number 1656:function, which is the 58:, other examples being 38:Triangular Numbers Plot 7947:Wedderburn–Etherington 7347:Lucky numbers of Euler 6662:Arithmetic progression 6099:Lagrange, Joseph Louis 6003:See equations 18 - 20. 5566:th triangular number. 5523: 4963: 4933: 4822: 4762: 4761:{\displaystyle =n^{2}} 4731: 4649: 4567: 4452: 4361: 4291: 4253: 4214: 4178: 4119: 3790: 3632: 3595: 3534: 3499: 3461: 3414: 3357: 3299: 3264: 3217: 3162: 3097: 2976: 2896: 2862: 2813: 2791: 2751: 2705: 2680: 2647: 2614: 2532: 2499: 2391: 2043: 1964: 1787: 1606:The triangular number 1603: 1538: 1518: 1498: 1478: 1458: 1432: 1410: 1136: 1097: 1071: 1033: 987: 965: 908: 860: 844:mathematical induction 828: 765: 706: 679: 622: 584: 553: 510: 493:plus one choose two". 470: 419: 254: 200: 39: 31: 8235:Prime omega functions 8052:Frobenius pseudoprime 7842:Combinatorial numbers 7711:Centered dodecahedral 7504:Primary pseudoperfect 7053:Hypergeometric series 6667:Geometric progression 6429:Centered cube numbers 6233:triangular cube roots 6060:10.1201/9780429430701 5882:The Ramanujan Journal 5524: 5111:= 4 years would lose 4958:straight cuts is the 4949: 4934: 4823: 4763: 4732: 4650: 4568: 4504:geometric progression 4453: 4362: 4292: 4233: 4215: 4158: 4099: 3900:is an odd square and 3791: 3606: 3596: 3500: 3465: 3415: 3374: 3365:binomial coefficients 3358: 3265: 3230: 3218: 3128: 3098: 3025:(81) minus the sixth 3013:-gonal number is the 2977: 2876: 2842: 2821:The sum of the first 2814: 2771: 2731: 2691: 2681: 2648: 2615: 2533: 2500: 2392: 2044: 1965: 1788: 1598: 1539: 1519: 1499: 1479: 1459: 1433: 1411: 1116: 1098: 1072: 1013: 988: 966: 888: 861: 829: 766: 707: 705:{\displaystyle T_{4}} 680: 623: 585: 583:{\displaystyle T_{n}} 554: 511: 471: 420: 234: 128: 99:0th triangular number 37: 22: 8694:-composition related 8494:Arithmetic functions 8096:Arithmetic functions 8032:Elliptic pseudoprime 7716:Centered icosahedral 7696:Centered tetrahedral 7033:Trigonometric series 6825:Properties of series 6672:Harmonic progression 6472:Dodecahedral numbers 5558:is an integer, then 5479: 5442:By analogy with the 4838: 4779: 4742: 4660: 4578: 4531: 4517:, in particular the 4371: 4303: 4230: 4096: 3693: 3371: 3227: 3125: 3049: 2839: 2728: 2716:th triangular number 2657: 2624: 2550: 2509: 2431: 2225: 2064: 1980: 1813: 1708: 1586:in about 816 in his 1549:Carl Friedrich Gauss 1528: 1508: 1488: 1468: 1442: 1422: 1109: 1081: 997: 977: 872: 850: 775: 718: 689: 632: 594: 567: 520: 500: 478:binomial coefficient 431: 330: 209: 52:equilateral triangle 9074:Proof without words 8620:Kaprekar's constant 8140:Colossally abundant 8027:Catalan pseudoprime 7927:Schröder–Hipparchus 7706:Centered octahedral 7582:Centered heptagonal 7572:Centered pentagonal 7562:Centered triangular 7162:and related numbers 7013:Formal power series 6589:8-hypercube numbers 6584:7-hypercube numbers 6579:6-hypercube numbers 6574:5-hypercube numbers 6544:Tesseractic numbers 6500:Tetrahedral numbers 6477:Icosahedral numbers 6393:Dodecagonal numbers 6215:"Triangular Number" 6175:"Arithmetic series" 6104:Elements of Algebra 5994:. Wolfram MathWorld 5992:"Triangular Number" 5990:Eric W. Weisstein. 5212: 5020:of an asset is the 4508:Kazimierz Szymiczek 3675:Proof without words 3642:Faulhaber's formula 2226: 2198: 1807:recurrence relation 1600:Proof without words 1457:{\displaystyle m+1} 1096:{\displaystyle m+1} 331: 314: 158:Tetrahedral numbers 9038:Mathematics portal 8980:Aronson's sequence 8726:Smarandache–Wellin 8483:-dependent numbers 8190:Primitive abundant 8077:Strong pseudoprime 8067:Perrin pseudoprime 8047:Fermat pseudoprime 7987:Wolstenholme prime 7811:Squared triangular 7597:Centered decagonal 7592:Centered nonagonal 7587:Centered octagonal 7577:Centered hexagonal 6811:Monotonic function 6730:Fibonacci sequence 6467:Octahedral numbers 6373:Heptagonal numbers 6363:Pentagonal numbers 6353:Triangular numbers 6212:Weisstein, Eric W. 6192:Triangular numbers 6025:10.1353/book.49475 5688:American Scientist 5519: 5204: 5159:in the third, and 4964: 4929: 4927: 4818: 4758: 4727: 4645: 4563: 4448: 4357: 4287: 4224:telescoping series 4210: 3786: 3658:{{{annotations}}} 3633: 3591: 3353: 3213: 3116:trapezoidal number 3093: 2972: 2833:tetrahedral number 2809: 2706: 2676: 2643: 2610: 2528: 2495: 2387: 2039: 1998: 1960: 1783: 1702:is equivalent to: 1604: 1534: 1514: 1494: 1474: 1454: 1428: 1406: 1404: 1093: 1067: 983: 961: 856: 824: 761: 702: 675: 618: 580: 549: 506: 496:The fact that the 476:is notation for a 466: 465: 415: 414: 412: 201: 149:Triangular numbers 40: 32: 9069:Integer sequences 9046: 9045: 9024: 9023: 8993: 8992: 8957: 8956: 8921: 8920: 8885: 8884: 8845: 8844: 8841: 8840: 8660: 8659: 8470: 8469: 8359: 8358: 8355: 8354: 8301:Aliquot sequences 8112:Divisor functions 8085: 8084: 8057:Lucas pseudoprime 8037:Euler pseudoprime 8022:Carmichael number 8000: 7999: 7955: 7954: 7832: 7831: 7828: 7827: 7824: 7823: 7785: 7784: 7673: 7672: 7630:Square triangular 7522: 7521: 7469: 7468: 7421: 7420: 7355: 7354: 7307: 7306: 7245: 7244: 7112: 7111: 7043:Generating series 6991: 6990: 6963:1 − 2 + 4 − 8 + ⋯ 6958:1 + 2 + 4 + 8 + ⋯ 6953:1 − 2 + 3 − 4 + ⋯ 6948:1 + 2 + 3 + 4 + ⋯ 6938:1 + 1 + 1 + 1 + ⋯ 6888: 6887: 6816:Periodic sequence 6785: 6784: 6770:Triangular number 6760:Pentagonal number 6740:Heptagonal number 6725:Complete sequence 6647:Integer sequences 6601: 6600: 6597: 6596: 6552: 6551: 6534:Pentatope numbers 6513: 6512: 6401: 6400: 6388:Decagonal numbers 6383:Nonagonal numbers 6378:Octagonal numbers 6368:Hexagonal numbers 6150:978-3-662-57968-8 6069:978-0-429-43070-1 5668:978-0-914098-91-1 5604:1 + 2 + 3 + 4 + ⋯ 5533:quadratic formula 5517: 5505: 5435: 5434: 4674: 4624: 4592: 4279: 4202: 4150: 4148: 4016:, ... etc. Given 3764: 3625:Pascal's triangle 3583: 3342: 3205: 3023:heptagonal number 2967: 2922: 2319: 2306: 2276: 2263: 2233: 2178: 2132: 2119: 2034: 2021: 1983: 1943: 1887: 1884: 1881: 1868: 1619:handshake problem 1537:{\displaystyle n} 1517:{\displaystyle 3} 1497:{\displaystyle 2} 1477:{\displaystyle 1} 1438:, it is true for 1431:{\displaystyle m} 1397: 1348: 1304: 1254: 1190: 1065: 986:{\displaystyle m} 953: 940: 859:{\displaystyle 1} 816: 673: 509:{\displaystyle n} 457: 402: 368: 338: 167:Pentatope numbers 131:Pascal's triangle 44:triangular number 9096: 9059:Figurate numbers 9036: 8999: 8968:Natural language 8963: 8927: 8895:Generated via a 8891: 8851: 8756:Digit-reassembly 8721:Self-descriptive 8525: 8490: 8476: 8427:Lucas–Carmichael 8417:Harmonic divisor 8365: 8291:Sparsely totient 8266:Highly cototient 8175:Multiply perfect 8165:Highly composite 8108: 8091: 8006: 7961: 7942:Telephone number 7838: 7796: 7777:Square pyramidal 7759:Stella octangula 7684: 7550: 7541: 7533:Figurate numbers 7528: 7475: 7427: 7361: 7313: 7251: 7155: 7139: 7132: 7125: 7116: 7102: 7101: 7028:Dirichlet series 6897: 6829: 6793: 6765:Polygonal number 6745:Hexagonal number 6718: 6652: 6628: 6621: 6614: 6605: 6564: 6524: 6412: 6283: 6270:Figurate numbers 6263: 6256: 6249: 6240: 6225: 6224: 6188: 6162: 6161: 6128: 6122: 6115: 6109: 6108: 6091: 6082: 6081: 6045: 6039: 6038: 6010: 6004: 6002: 6000: 5999: 5987: 5981: 5980: 5978: 5976: 5956:(507): 423–431. 5941: 5935: 5934: 5932: 5920: 5914: 5913: 5877: 5871: 5866: 5860: 5855: 5849: 5848: 5814: 5809: 5799: 5793: 5792: 5784: 5778: 5777: 5775: 5773: 5768:on 10 March 2016 5764:. Archived from 5754: 5748: 5741: 5735: 5732: 5726: 5725: 5723: 5721: 5709: 5703: 5702: 5700: 5699: 5679: 5673: 5672: 5649: 5643: 5642: 5631: 5593: 5587: 5578:, by analogy to 5570:Alternative name 5565: 5561: 5557: 5553: 5549: 5538: 5535:. So an integer 5528: 5526: 5525: 5520: 5518: 5513: 5506: 5492: 5489: 5474: 5459: 5453: 5449: 5213: 5190: 5188: 5187: 5184: 5181: 5174: 5172: 5171: 5168: 5165: 5158: 5156: 5155: 5152: 5149: 5142: 5140: 5139: 5136: 5133: 5126: 5124: 5123: 5120: 5117: 5110: 5104: 5098: 5092: 5086: 5080: 5079: 5077: 5076: 5066: 5063: 5040: 5034: 5012: 5000: 4987: 4975: 4954:obtainable with 4938: 4936: 4935: 4930: 4928: 4900: 4865: 4844: 4827: 4825: 4824: 4819: 4817: 4816: 4804: 4803: 4791: 4790: 4767: 4765: 4764: 4759: 4757: 4756: 4736: 4734: 4733: 4728: 4726: 4725: 4686: 4685: 4675: 4667: 4654: 4652: 4651: 4646: 4625: 4617: 4593: 4585: 4572: 4570: 4569: 4564: 4562: 4561: 4549: 4548: 4487: 4476: 4469: 4457: 4455: 4454: 4449: 4444: 4443: 4428: 4427: 4409: 4408: 4399: 4398: 4386: 4385: 4366: 4364: 4363: 4358: 4347: 4346: 4334: 4333: 4321: 4320: 4296: 4294: 4293: 4288: 4280: 4278: 4255: 4252: 4247: 4219: 4217: 4216: 4211: 4203: 4201: 4194: 4193: 4180: 4177: 4172: 4151: 4149: 4144: 4137: 4136: 4126: 4121: 4118: 4113: 4084: 4071: 4058: 4045: 4032: 4021: 4015: 4007: 3999: 3991: 3983: 3975: 3967: 3959: 3953: 3947: 3930: 3924: 3923: 3921: 3920: 3917: 3914: 3899: 3893: 3883: 3867:91 = 9 × 10 + 1 3804: 3795: 3793: 3792: 3787: 3785: 3784: 3783: 3782: 3765: 3760: 3750: 3749: 3737: 3736: 3726: 3721: 3720: 3705: 3704: 3666: 3654: 3636:Other properties 3629:pentatope number 3600: 3598: 3597: 3592: 3590: 3589: 3588: 3579: 3566: 3565: 3554: 3544: 3543: 3533: 3532: 3531: 3521: 3514: 3513: 3498: 3497: 3496: 3486: 3479: 3478: 3460: 3459: 3458: 3442: 3435: 3434: 3413: 3412: 3411: 3401: 3394: 3393: 3362: 3360: 3359: 3354: 3349: 3348: 3347: 3338: 3331: 3330: 3319: 3309: 3308: 3298: 3297: 3296: 3286: 3279: 3278: 3263: 3262: 3261: 3251: 3244: 3243: 3222: 3220: 3219: 3214: 3212: 3211: 3210: 3201: 3194: 3193: 3182: 3172: 3171: 3161: 3160: 3159: 3149: 3142: 3141: 3110: 3102: 3100: 3099: 3094: 3086: 3085: 3064: 3063: 3044: 3038: 3027:hexagonal number 3020: 3012: 3004: 2996: 2989: 2981: 2979: 2978: 2973: 2968: 2963: 2928: 2923: 2918: 2898: 2895: 2890: 2872: 2871: 2861: 2856: 2830: 2824: 2818: 2816: 2815: 2810: 2805: 2804: 2799: 2795: 2790: 2785: 2761: 2760: 2750: 2745: 2723: 2715: 2703: 2697: 2685: 2683: 2682: 2677: 2669: 2668: 2652: 2650: 2649: 2644: 2636: 2635: 2619: 2617: 2616: 2611: 2603: 2602: 2584: 2583: 2562: 2561: 2537: 2535: 2534: 2529: 2521: 2520: 2504: 2502: 2501: 2496: 2494: 2490: 2483: 2482: 2465: 2464: 2449: 2448: 2413: 2407: 2396: 2394: 2393: 2388: 2383: 2382: 2373: 2372: 2354: 2353: 2338: 2337: 2325: 2321: 2320: 2312: 2307: 2302: 2301: 2292: 2282: 2278: 2277: 2269: 2264: 2259: 2258: 2249: 2239: 2235: 2234: 2229: 2228: 2227: 2224: 2223: 2218: 2214: 2184: 2179: 2174: 2173: 2168: 2164: 2148: 2138: 2134: 2133: 2125: 2120: 2115: 2114: 2105: 2095: 2094: 2076: 2075: 2048: 2046: 2045: 2040: 2035: 2027: 2022: 2020: 2019: 2010: 2009: 2000: 1997: 1969: 1967: 1966: 1961: 1953: 1952: 1941: 1916: 1915: 1897: 1896: 1885: 1882: 1879: 1875: 1874: 1873: 1860: 1847: 1846: 1825: 1824: 1792: 1790: 1789: 1784: 1671:Termial function 1665: 1651: 1645: 1633: 1627: 1616: 1577: 1570: 1569: 1567: 1566: 1563: 1560: 1543: 1541: 1540: 1535: 1523: 1521: 1520: 1515: 1503: 1501: 1500: 1495: 1483: 1481: 1480: 1475: 1463: 1461: 1460: 1455: 1437: 1435: 1434: 1429: 1415: 1413: 1412: 1407: 1405: 1398: 1393: 1361: 1353: 1349: 1344: 1328: 1327: 1317: 1309: 1305: 1300: 1278: 1277: 1267: 1259: 1255: 1250: 1215: 1207: 1191: 1186: 1166: 1135: 1130: 1102: 1100: 1099: 1094: 1076: 1074: 1073: 1068: 1066: 1061: 1041: 1032: 1027: 1009: 1008: 992: 990: 989: 984: 970: 968: 967: 962: 954: 946: 941: 936: 916: 907: 902: 884: 883: 865: 863: 862: 857: 839: 833: 831: 830: 825: 817: 812: 792: 787: 786: 770: 768: 767: 762: 733: 732: 711: 709: 708: 703: 701: 700: 684: 682: 681: 676: 674: 669: 649: 644: 643: 627: 625: 624: 619: 589: 587: 586: 581: 579: 578: 558: 556: 555: 550: 545: 515: 513: 512: 507: 492: 486: 475: 473: 472: 467: 464: 463: 462: 453: 441: 424: 422: 421: 416: 413: 409: 408: 407: 398: 386: 373: 369: 364: 344: 339: 334: 333: 332: 304: 303: 293: 285: 253: 248: 226: 225: 193: 183: 173: 164: 155: 146: 137: 112: 92: 83: 77: 71: 9104: 9103: 9099: 9098: 9097: 9095: 9094: 9093: 9089:Simplex numbers 9049: 9048: 9047: 9042: 9020: 9016:Strobogrammatic 9007: 8989: 8971: 8953: 8935: 8917: 8899: 8881: 8858: 8837: 8821: 8780:Divisor-related 8775: 8735: 8686: 8656: 8593: 8577: 8556: 8523: 8496: 8484: 8466: 8378: 8377:related numbers 8351: 8328: 8295: 8286:Perfect totient 8252: 8229: 8160:Highly abundant 8102: 8081: 8013: 7996: 7968: 7951: 7937:Stirling second 7843: 7820: 7781: 7763: 7720: 7669: 7606: 7567:Centered square 7535: 7518: 7480: 7465: 7432: 7417: 7369: 7368:defined numbers 7351: 7318: 7303: 7274:Double Mersenne 7260: 7241: 7163: 7149: 7147:natural numbers 7143: 7113: 7108: 7090: 7047: 6996:Kinds of series 6987: 6926: 6893:Explicit series 6884: 6858: 6820: 6806:Cauchy sequence 6794: 6781: 6735:Figurate number 6712: 6706: 6697:Powers of three 6641: 6632: 6602: 6593: 6548: 6509: 6486: 6448: 6397: 6339: 6272: 6267: 6210: 6209: 6173: 6170: 6165: 6151: 6130: 6129: 6125: 6116: 6112: 6095:Euler, Leonhard 6093: 6092: 6085: 6070: 6047: 6046: 6042: 6035: 6012: 6011: 6007: 5997: 5995: 5989: 5988: 5984: 5974: 5972: 5962:10.2307/3621134 5943: 5942: 5938: 5922: 5921: 5917: 5879: 5878: 5874: 5867: 5863: 5856: 5852: 5812: 5805: 5801: 5800: 5796: 5787:Knuth, Donald. 5786: 5785: 5781: 5771: 5769: 5762:MathCircles.org 5756: 5755: 5751: 5742: 5738: 5733: 5729: 5719: 5717: 5711: 5710: 5706: 5697: 5695: 5681: 5680: 5676: 5669: 5653:Spivak, Michael 5651: 5650: 5646: 5633: 5632: 5628: 5624: 5600: 5589: 5583: 5572: 5563: 5559: 5555: 5551: 5543: 5536: 5490: 5477: 5476: 5469: 5461: 5455: 5451: 5447: 5440: 5364: 5210: 5185: 5182: 5179: 5178: 5176: 5169: 5166: 5163: 5162: 5160: 5153: 5150: 5147: 5146: 5144: 5143:in the second, 5137: 5134: 5131: 5130: 5128: 5121: 5118: 5115: 5114: 5112: 5106: 5100: 5094: 5088: 5082: 5075: 5067: 5064: 5055: 5054: 5052: 5042: 5036: 5033: 5025: 5011: 5002: 4996: 4986: 4977: 4971: 4944: 4926: 4925: 4920: 4915: 4910: 4905: 4898: 4897: 4892: 4887: 4882: 4877: 4872: 4866: 4864: 4859: 4854: 4849: 4836: 4835: 4808: 4795: 4782: 4777: 4776: 4773:Theon of Smyrna 4748: 4740: 4739: 4658: 4657: 4576: 4575: 4553: 4534: 4529: 4528: 4515:theta functions 4485: 4475:num = Δ + Δ + Δ 4474: 4468: 4462: 4429: 4413: 4400: 4390: 4374: 4369: 4368: 4338: 4325: 4306: 4301: 4300: 4228: 4227: 4185: 4128: 4094: 4093: 4088:The sum of the 4083: 4073: 4070: 4060: 4057: 4047: 4044: 4034: 4031: 4023: 4017: 4009: 4001: 3993: 3985: 3977: 3969: 3961: 3955: 3949: 3941: 3932: 3926: 3918: 3915: 3909: 3908: 3906: 3901: 3895: 3885: 3879: 3870: 3864:78 = 9 × 8 + 6 3861:66 = 9 × 7 + 3 3858:55 = 9 × 6 + 1 3849:28 = 9 × 3 + 1 3846:21 = 9 × 2 + 3 3843:15 = 9 × 1 + 6 3840:10 = 9 × 1 + 1 3802: 3797: 3774: 3769: 3741: 3728: 3727: 3706: 3696: 3691: 3690: 3680: 3679: 3678: 3673: 3668: 3667: 3660: 3655: 3638: 3557: 3556: 3549: 3535: 3523: 3505: 3488: 3470: 3444: 3420: 3403: 3379: 3369: 3368: 3322: 3321: 3314: 3300: 3288: 3270: 3253: 3235: 3225: 3224: 3185: 3184: 3177: 3163: 3151: 3133: 3123: 3122: 3106: 3071: 3055: 3047: 3046: 3040: 3034: 3014: 3006: 3000: 2992: 2985: 2929: 2899: 2863: 2837: 2836: 2826: 2822: 2770: 2766: 2765: 2752: 2726: 2725: 2719: 2711: 2699: 2693: 2660: 2655: 2654: 2627: 2622: 2621: 2588: 2569: 2553: 2548: 2547: 2512: 2507: 2506: 2474: 2470: 2466: 2456: 2434: 2429: 2428: 2414: 2374: 2358: 2345: 2329: 2293: 2290: 2286: 2250: 2247: 2243: 2204: 2200: 2199: 2185: 2154: 2150: 2149: 2146: 2142: 2106: 2103: 2099: 2080: 2067: 2062: 2061: 2054: 2011: 2001: 1978: 1977: 1944: 1901: 1888: 1855: 1832: 1816: 1811: 1810: 1804: 1706: 1705: 1661: 1647: 1646:. The function 1644: 1635: 1629: 1622: 1615: 1607: 1572: 1564: 1561: 1556: 1555: 1553: 1552: 1526: 1525: 1506: 1505: 1486: 1485: 1466: 1465: 1440: 1439: 1420: 1419: 1403: 1402: 1362: 1351: 1350: 1319: 1318: 1307: 1306: 1269: 1268: 1257: 1256: 1216: 1205: 1204: 1167: 1158: 1107: 1106: 1103:to this yields 1079: 1078: 1042: 1000: 995: 994: 975: 974: 917: 875: 870: 869: 848: 847: 840: 793: 778: 773: 772: 724: 716: 715: 692: 687: 686: 685:. The example 650: 635: 630: 629: 592: 591: 570: 565: 564: 518: 517: 498: 497: 488: 481: 443: 436: 429: 428: 425: 411: 410: 388: 381: 371: 370: 345: 295: 294: 283: 282: 227: 217: 207: 206: 199: 191: 189: 181: 179: 171: 169: 162: 160: 153: 151: 144: 142: 140:Natural numbers 135: 123: 108: 105: 88: 85:natural numbers 79: 73: 67: 56:figurate number 48:triangle number 29: 17: 16:Figurate number 12: 11: 5: 9102: 9100: 9092: 9091: 9086: 9081: 9076: 9071: 9066: 9061: 9051: 9050: 9044: 9043: 9041: 9040: 9029: 9026: 9025: 9022: 9021: 9019: 9018: 9012: 9009: 9008: 9002: 8995: 8994: 8991: 8990: 8988: 8987: 8982: 8976: 8973: 8972: 8966: 8959: 8958: 8955: 8954: 8952: 8951: 8949:Sorting number 8946: 8944:Pancake number 8940: 8937: 8936: 8930: 8923: 8922: 8919: 8918: 8916: 8915: 8910: 8904: 8901: 8900: 8894: 8887: 8886: 8883: 8882: 8880: 8879: 8874: 8869: 8863: 8860: 8859: 8856:Binary numbers 8854: 8847: 8846: 8843: 8842: 8839: 8838: 8836: 8835: 8829: 8827: 8823: 8822: 8820: 8819: 8814: 8809: 8804: 8799: 8794: 8789: 8783: 8781: 8777: 8776: 8774: 8773: 8768: 8763: 8758: 8753: 8747: 8745: 8737: 8736: 8734: 8733: 8728: 8723: 8718: 8713: 8708: 8703: 8697: 8695: 8688: 8687: 8685: 8684: 8683: 8682: 8671: 8669: 8666:P-adic numbers 8662: 8661: 8658: 8657: 8655: 8654: 8653: 8652: 8642: 8637: 8632: 8627: 8622: 8617: 8612: 8607: 8601: 8599: 8595: 8594: 8592: 8591: 8585: 8583: 8582:Coding-related 8579: 8578: 8576: 8575: 8570: 8564: 8562: 8558: 8557: 8555: 8554: 8549: 8544: 8539: 8533: 8531: 8522: 8521: 8520: 8519: 8517:Multiplicative 8514: 8503: 8501: 8486: 8485: 8481:Numeral system 8479: 8472: 8471: 8468: 8467: 8465: 8464: 8459: 8454: 8449: 8444: 8439: 8434: 8429: 8424: 8419: 8414: 8409: 8404: 8399: 8394: 8389: 8383: 8380: 8379: 8368: 8361: 8360: 8357: 8356: 8353: 8352: 8350: 8349: 8344: 8338: 8336: 8330: 8329: 8327: 8326: 8321: 8316: 8311: 8305: 8303: 8297: 8296: 8294: 8293: 8288: 8283: 8278: 8273: 8271:Highly totient 8268: 8262: 8260: 8254: 8253: 8251: 8250: 8245: 8239: 8237: 8231: 8230: 8228: 8227: 8222: 8217: 8212: 8207: 8202: 8197: 8192: 8187: 8182: 8177: 8172: 8167: 8162: 8157: 8152: 8147: 8142: 8137: 8132: 8127: 8125:Almost perfect 8122: 8116: 8114: 8104: 8103: 8094: 8087: 8086: 8083: 8082: 8080: 8079: 8074: 8069: 8064: 8059: 8054: 8049: 8044: 8039: 8034: 8029: 8024: 8018: 8015: 8014: 8009: 8002: 8001: 7998: 7997: 7995: 7994: 7989: 7984: 7979: 7973: 7970: 7969: 7964: 7957: 7956: 7953: 7952: 7950: 7949: 7944: 7939: 7934: 7932:Stirling first 7929: 7924: 7919: 7914: 7909: 7904: 7899: 7894: 7889: 7884: 7879: 7874: 7869: 7864: 7859: 7854: 7848: 7845: 7844: 7841: 7834: 7833: 7830: 7829: 7826: 7825: 7822: 7821: 7819: 7818: 7813: 7808: 7802: 7800: 7793: 7787: 7786: 7783: 7782: 7780: 7779: 7773: 7771: 7765: 7764: 7762: 7761: 7756: 7751: 7746: 7741: 7736: 7730: 7728: 7722: 7721: 7719: 7718: 7713: 7708: 7703: 7698: 7692: 7690: 7681: 7675: 7674: 7671: 7670: 7668: 7667: 7662: 7657: 7652: 7647: 7642: 7637: 7632: 7627: 7622: 7616: 7614: 7608: 7607: 7605: 7604: 7599: 7594: 7589: 7584: 7579: 7574: 7569: 7564: 7558: 7556: 7547: 7537: 7536: 7531: 7524: 7523: 7520: 7519: 7517: 7516: 7511: 7506: 7501: 7496: 7491: 7485: 7482: 7481: 7478: 7471: 7470: 7467: 7466: 7464: 7463: 7458: 7453: 7448: 7443: 7437: 7434: 7433: 7430: 7423: 7422: 7419: 7418: 7416: 7415: 7410: 7405: 7400: 7395: 7390: 7385: 7380: 7374: 7371: 7370: 7364: 7357: 7356: 7353: 7352: 7350: 7349: 7344: 7339: 7334: 7329: 7323: 7320: 7319: 7316: 7309: 7308: 7305: 7304: 7302: 7301: 7296: 7291: 7286: 7281: 7276: 7271: 7265: 7262: 7261: 7254: 7247: 7246: 7243: 7242: 7240: 7239: 7234: 7229: 7224: 7219: 7214: 7209: 7204: 7199: 7194: 7189: 7184: 7179: 7174: 7168: 7165: 7164: 7158: 7151: 7150: 7144: 7142: 7141: 7134: 7127: 7119: 7110: 7109: 7107: 7106: 7095: 7092: 7091: 7089: 7088: 7083: 7078: 7073: 7068: 7063: 7057: 7055: 7049: 7048: 7046: 7045: 7040: 7038:Fourier series 7035: 7030: 7025: 7023:Puiseux series 7020: 7018:Laurent series 7015: 7010: 7005: 6999: 6997: 6993: 6992: 6989: 6988: 6986: 6985: 6980: 6975: 6970: 6965: 6960: 6955: 6950: 6945: 6940: 6934: 6932: 6928: 6927: 6925: 6924: 6919: 6914: 6909: 6903: 6901: 6894: 6890: 6889: 6886: 6885: 6883: 6882: 6877: 6872: 6866: 6864: 6860: 6859: 6857: 6856: 6851: 6846: 6841: 6835: 6833: 6826: 6822: 6821: 6819: 6818: 6813: 6808: 6802: 6800: 6796: 6795: 6788: 6786: 6783: 6782: 6780: 6779: 6778: 6777: 6767: 6762: 6757: 6752: 6747: 6742: 6737: 6732: 6727: 6721: 6719: 6708: 6707: 6705: 6704: 6699: 6694: 6689: 6684: 6679: 6674: 6669: 6664: 6658: 6656: 6649: 6643: 6642: 6633: 6631: 6630: 6623: 6616: 6608: 6599: 6598: 6595: 6594: 6592: 6591: 6586: 6581: 6576: 6570: 6568: 6561: 6554: 6553: 6550: 6549: 6547: 6546: 6541: 6536: 6530: 6528: 6521: 6515: 6514: 6511: 6510: 6508: 6507: 6502: 6496: 6494: 6488: 6487: 6485: 6484: 6479: 6474: 6469: 6464: 6458: 6456: 6450: 6449: 6447: 6446: 6441: 6436: 6431: 6426: 6420: 6418: 6409: 6403: 6402: 6399: 6398: 6396: 6395: 6390: 6385: 6380: 6375: 6370: 6365: 6360: 6358:Square numbers 6355: 6349: 6347: 6341: 6340: 6338: 6337: 6332: 6327: 6322: 6317: 6312: 6307: 6302: 6297: 6291: 6289: 6280: 6274: 6273: 6268: 6266: 6265: 6258: 6251: 6243: 6237: 6236: 6226: 6207: 6198: 6189: 6169: 6168:External links 6166: 6164: 6163: 6149: 6123: 6110: 6083: 6068: 6040: 6033: 6005: 5982: 5936: 5915: 5888:(4): 407–434. 5872: 5861: 5850: 5794: 5779: 5749: 5736: 5727: 5712:Eves, Howard. 5704: 5682:Hayes, Brian. 5674: 5667: 5644: 5625: 5623: 5620: 5619: 5618: 5612: 5606: 5599: 5596: 5571: 5568: 5541:if and only if 5539:is triangular 5516: 5512: 5509: 5504: 5501: 5498: 5495: 5487: 5484: 5465: 5454:as the number 5439: 5436: 5433: 5432: 5429: 5426: 5423: 5420: 5417: 5414: 5411: 5408: 5405: 5402: 5399: 5396: 5393: 5390: 5387: 5384: 5381: 5378: 5375: 5372: 5369: 5366: 5362: 5357: 5356: 5353: 5350: 5347: 5344: 5341: 5338: 5335: 5332: 5329: 5326: 5323: 5320: 5317: 5314: 5311: 5308: 5305: 5302: 5299: 5296: 5293: 5290: 5284: 5283: 5280: 5277: 5274: 5271: 5268: 5265: 5262: 5259: 5256: 5253: 5250: 5247: 5244: 5241: 5238: 5235: 5232: 5229: 5226: 5223: 5220: 5217: 5199:game designers 5071: 5029: 5006: 4981: 4943: 4940: 4924: 4921: 4919: 4916: 4914: 4911: 4909: 4906: 4904: 4901: 4899: 4896: 4893: 4891: 4888: 4886: 4883: 4881: 4878: 4876: 4873: 4871: 4868: 4867: 4863: 4860: 4858: 4855: 4853: 4850: 4848: 4845: 4843: 4815: 4811: 4807: 4802: 4798: 4794: 4789: 4785: 4769: 4768: 4755: 4751: 4747: 4737: 4724: 4719: 4716: 4713: 4710: 4707: 4704: 4701: 4698: 4695: 4692: 4689: 4684: 4679: 4673: 4670: 4665: 4655: 4644: 4641: 4638: 4635: 4632: 4629: 4623: 4620: 4615: 4612: 4609: 4606: 4603: 4600: 4597: 4591: 4588: 4583: 4573: 4560: 4556: 4552: 4547: 4544: 4541: 4537: 4466: 4447: 4442: 4439: 4436: 4432: 4426: 4423: 4420: 4416: 4412: 4407: 4403: 4397: 4393: 4389: 4384: 4381: 4377: 4356: 4353: 4350: 4345: 4341: 4337: 4332: 4328: 4324: 4319: 4316: 4313: 4309: 4286: 4283: 4277: 4274: 4271: 4268: 4265: 4262: 4258: 4251: 4246: 4243: 4240: 4236: 4209: 4206: 4200: 4197: 4192: 4188: 4183: 4176: 4171: 4168: 4165: 4161: 4157: 4154: 4147: 4143: 4140: 4135: 4131: 4124: 4117: 4112: 4109: 4106: 4102: 4077: 4064: 4051: 4038: 4027: 3937: 3837:6 = 9 × 0 + 6 3834:3 = 9 × 0 + 3 3831:1 = 9 × 0 + 1 3828: 3807:Mersenne prime 3800: 3781: 3777: 3772: 3768: 3763: 3759: 3756: 3753: 3748: 3744: 3740: 3735: 3731: 3724: 3719: 3716: 3713: 3709: 3703: 3699: 3687:perfect number 3670: 3669: 3661: 3656: 3649: 3648: 3647: 3646: 3637: 3634: 3631:, and so forth 3587: 3582: 3578: 3575: 3572: 3569: 3564: 3560: 3553: 3547: 3542: 3538: 3530: 3526: 3520: 3517: 3512: 3508: 3503: 3495: 3491: 3485: 3482: 3477: 3473: 3468: 3464: 3457: 3454: 3451: 3447: 3441: 3438: 3433: 3430: 3427: 3423: 3418: 3410: 3406: 3400: 3397: 3392: 3389: 3386: 3382: 3377: 3352: 3346: 3341: 3337: 3334: 3329: 3325: 3318: 3312: 3307: 3303: 3295: 3291: 3285: 3282: 3277: 3273: 3268: 3260: 3256: 3250: 3247: 3242: 3238: 3233: 3209: 3204: 3200: 3197: 3192: 3188: 3181: 3175: 3170: 3166: 3158: 3154: 3148: 3145: 3140: 3136: 3131: 3092: 3089: 3084: 3081: 3078: 3074: 3070: 3067: 3062: 3058: 3054: 2971: 2966: 2962: 2959: 2956: 2953: 2950: 2947: 2944: 2941: 2938: 2935: 2932: 2926: 2921: 2917: 2914: 2911: 2908: 2905: 2902: 2894: 2889: 2886: 2883: 2879: 2875: 2870: 2866: 2860: 2855: 2852: 2849: 2845: 2808: 2803: 2798: 2794: 2789: 2784: 2781: 2778: 2774: 2769: 2764: 2759: 2755: 2749: 2744: 2741: 2738: 2734: 2710:square of the 2675: 2672: 2667: 2663: 2642: 2639: 2634: 2630: 2609: 2606: 2601: 2598: 2595: 2591: 2587: 2582: 2579: 2576: 2572: 2568: 2565: 2560: 2556: 2527: 2524: 2519: 2515: 2493: 2489: 2486: 2481: 2477: 2473: 2469: 2463: 2459: 2455: 2452: 2447: 2444: 2441: 2437: 2420:, is called a 2418:§ Formula 2401: 2386: 2381: 2377: 2371: 2368: 2365: 2361: 2357: 2352: 2348: 2344: 2341: 2336: 2332: 2328: 2324: 2318: 2315: 2310: 2305: 2300: 2296: 2289: 2285: 2281: 2275: 2272: 2267: 2262: 2257: 2253: 2246: 2242: 2238: 2232: 2222: 2217: 2213: 2210: 2207: 2203: 2194: 2191: 2188: 2182: 2177: 2172: 2167: 2163: 2160: 2157: 2153: 2145: 2141: 2137: 2131: 2128: 2123: 2118: 2113: 2109: 2102: 2098: 2093: 2090: 2087: 2083: 2079: 2074: 2070: 2053: 2050: 2038: 2033: 2030: 2025: 2018: 2014: 2008: 2004: 1996: 1993: 1990: 1986: 1959: 1956: 1951: 1947: 1940: 1937: 1934: 1931: 1928: 1925: 1922: 1919: 1914: 1911: 1908: 1904: 1900: 1895: 1891: 1878: 1872: 1867: 1864: 1859: 1853: 1850: 1845: 1842: 1839: 1835: 1831: 1828: 1823: 1819: 1782: 1779: 1776: 1773: 1770: 1767: 1764: 1761: 1758: 1755: 1752: 1749: 1746: 1743: 1740: 1737: 1734: 1731: 1728: 1725: 1722: 1719: 1716: 1713: 1639: 1611: 1544:by induction. 1533: 1513: 1493: 1473: 1453: 1450: 1447: 1427: 1401: 1396: 1392: 1389: 1386: 1383: 1380: 1377: 1374: 1371: 1368: 1365: 1359: 1356: 1354: 1352: 1347: 1343: 1340: 1337: 1334: 1331: 1326: 1322: 1315: 1312: 1310: 1308: 1303: 1299: 1296: 1293: 1290: 1287: 1284: 1281: 1276: 1272: 1265: 1262: 1260: 1258: 1253: 1249: 1246: 1243: 1240: 1237: 1234: 1231: 1228: 1225: 1222: 1219: 1213: 1210: 1208: 1206: 1203: 1200: 1197: 1194: 1189: 1185: 1182: 1179: 1176: 1173: 1170: 1164: 1161: 1159: 1157: 1154: 1151: 1148: 1145: 1142: 1139: 1134: 1129: 1126: 1123: 1119: 1115: 1114: 1092: 1089: 1086: 1064: 1060: 1057: 1054: 1051: 1048: 1045: 1039: 1036: 1031: 1026: 1023: 1020: 1016: 1012: 1007: 1003: 982: 960: 957: 952: 949: 944: 939: 935: 932: 929: 926: 923: 920: 914: 911: 906: 901: 898: 895: 891: 887: 882: 878: 855: 823: 820: 815: 811: 808: 805: 802: 799: 796: 790: 785: 781: 760: 757: 754: 751: 748: 745: 742: 739: 736: 731: 727: 723: 714: 699: 695: 672: 668: 665: 662: 659: 656: 653: 647: 642: 638: 617: 614: 611: 608: 605: 602: 599: 577: 573: 548: 544: 540: 537: 534: 531: 528: 525: 505: 461: 456: 452: 449: 446: 440: 406: 401: 397: 394: 391: 385: 379: 376: 374: 372: 367: 363: 360: 357: 354: 351: 348: 342: 337: 329: 326: 323: 320: 317: 310: 307: 302: 298: 291: 288: 286: 284: 281: 278: 275: 272: 269: 266: 263: 260: 257: 252: 247: 244: 241: 237: 233: 230: 228: 224: 220: 216: 215: 205: 190: 180: 170: 161: 152: 143: 134: 122: 119: 103: 60:square numbers 27: 15: 13: 10: 9: 6: 4: 3: 2: 9101: 9090: 9087: 9085: 9082: 9080: 9077: 9075: 9072: 9070: 9067: 9065: 9062: 9060: 9057: 9056: 9054: 9039: 9035: 9031: 9030: 9027: 9017: 9014: 9013: 9010: 9005: 9000: 8996: 8986: 8983: 8981: 8978: 8977: 8974: 8969: 8964: 8960: 8950: 8947: 8945: 8942: 8941: 8938: 8933: 8928: 8924: 8914: 8911: 8909: 8906: 8905: 8902: 8898: 8892: 8888: 8878: 8875: 8873: 8870: 8868: 8865: 8864: 8861: 8857: 8852: 8848: 8834: 8831: 8830: 8828: 8824: 8818: 8815: 8813: 8810: 8808: 8807:Polydivisible 8805: 8803: 8800: 8798: 8795: 8793: 8790: 8788: 8785: 8784: 8782: 8778: 8772: 8769: 8767: 8764: 8762: 8759: 8757: 8754: 8752: 8749: 8748: 8746: 8743: 8738: 8732: 8729: 8727: 8724: 8722: 8719: 8717: 8714: 8712: 8709: 8707: 8704: 8702: 8699: 8698: 8696: 8693: 8689: 8681: 8678: 8677: 8676: 8673: 8672: 8670: 8667: 8663: 8651: 8648: 8647: 8646: 8643: 8641: 8638: 8636: 8633: 8631: 8628: 8626: 8623: 8621: 8618: 8616: 8613: 8611: 8608: 8606: 8603: 8602: 8600: 8596: 8590: 8587: 8586: 8584: 8580: 8574: 8571: 8569: 8566: 8565: 8563: 8561:Digit product 8559: 8553: 8550: 8548: 8545: 8543: 8540: 8538: 8535: 8534: 8532: 8530: 8526: 8518: 8515: 8513: 8510: 8509: 8508: 8505: 8504: 8502: 8500: 8495: 8491: 8487: 8482: 8477: 8473: 8463: 8460: 8458: 8455: 8453: 8450: 8448: 8445: 8443: 8440: 8438: 8435: 8433: 8430: 8428: 8425: 8423: 8420: 8418: 8415: 8413: 8410: 8408: 8405: 8403: 8400: 8398: 8397:Erdős–Nicolas 8395: 8393: 8390: 8388: 8385: 8384: 8381: 8376: 8372: 8366: 8362: 8348: 8345: 8343: 8340: 8339: 8337: 8335: 8331: 8325: 8322: 8320: 8317: 8315: 8312: 8310: 8307: 8306: 8304: 8302: 8298: 8292: 8289: 8287: 8284: 8282: 8279: 8277: 8274: 8272: 8269: 8267: 8264: 8263: 8261: 8259: 8255: 8249: 8246: 8244: 8241: 8240: 8238: 8236: 8232: 8226: 8223: 8221: 8218: 8216: 8215:Superabundant 8213: 8211: 8208: 8206: 8203: 8201: 8198: 8196: 8193: 8191: 8188: 8186: 8183: 8181: 8178: 8176: 8173: 8171: 8168: 8166: 8163: 8161: 8158: 8156: 8153: 8151: 8148: 8146: 8143: 8141: 8138: 8136: 8133: 8131: 8128: 8126: 8123: 8121: 8118: 8117: 8115: 8113: 8109: 8105: 8101: 8097: 8092: 8088: 8078: 8075: 8073: 8070: 8068: 8065: 8063: 8060: 8058: 8055: 8053: 8050: 8048: 8045: 8043: 8040: 8038: 8035: 8033: 8030: 8028: 8025: 8023: 8020: 8019: 8016: 8012: 8007: 8003: 7993: 7990: 7988: 7985: 7983: 7980: 7978: 7975: 7974: 7971: 7967: 7962: 7958: 7948: 7945: 7943: 7940: 7938: 7935: 7933: 7930: 7928: 7925: 7923: 7920: 7918: 7915: 7913: 7910: 7908: 7905: 7903: 7900: 7898: 7895: 7893: 7890: 7888: 7885: 7883: 7880: 7878: 7875: 7873: 7870: 7868: 7865: 7863: 7860: 7858: 7855: 7853: 7850: 7849: 7846: 7839: 7835: 7817: 7814: 7812: 7809: 7807: 7804: 7803: 7801: 7797: 7794: 7792: 7791:4-dimensional 7788: 7778: 7775: 7774: 7772: 7770: 7766: 7760: 7757: 7755: 7752: 7750: 7747: 7745: 7742: 7740: 7737: 7735: 7732: 7731: 7729: 7727: 7723: 7717: 7714: 7712: 7709: 7707: 7704: 7702: 7701:Centered cube 7699: 7697: 7694: 7693: 7691: 7689: 7685: 7682: 7680: 7679:3-dimensional 7676: 7666: 7663: 7661: 7658: 7656: 7653: 7651: 7648: 7646: 7643: 7641: 7638: 7636: 7633: 7631: 7628: 7626: 7623: 7621: 7618: 7617: 7615: 7613: 7609: 7603: 7600: 7598: 7595: 7593: 7590: 7588: 7585: 7583: 7580: 7578: 7575: 7573: 7570: 7568: 7565: 7563: 7560: 7559: 7557: 7555: 7551: 7548: 7546: 7545:2-dimensional 7542: 7538: 7534: 7529: 7525: 7515: 7512: 7510: 7507: 7505: 7502: 7500: 7497: 7495: 7492: 7490: 7489:Nonhypotenuse 7487: 7486: 7483: 7476: 7472: 7462: 7459: 7457: 7454: 7452: 7449: 7447: 7444: 7442: 7439: 7438: 7435: 7428: 7424: 7414: 7411: 7409: 7406: 7404: 7401: 7399: 7396: 7394: 7391: 7389: 7386: 7384: 7381: 7379: 7376: 7375: 7372: 7367: 7362: 7358: 7348: 7345: 7343: 7340: 7338: 7335: 7333: 7330: 7328: 7325: 7324: 7321: 7314: 7310: 7300: 7297: 7295: 7292: 7290: 7287: 7285: 7282: 7280: 7277: 7275: 7272: 7270: 7267: 7266: 7263: 7258: 7252: 7248: 7238: 7235: 7233: 7230: 7228: 7227:Perfect power 7225: 7223: 7220: 7218: 7217:Seventh power 7215: 7213: 7210: 7208: 7205: 7203: 7200: 7198: 7195: 7193: 7190: 7188: 7185: 7183: 7180: 7178: 7175: 7173: 7170: 7169: 7166: 7161: 7156: 7152: 7148: 7140: 7135: 7133: 7128: 7126: 7121: 7120: 7117: 7105: 7097: 7096: 7093: 7087: 7084: 7082: 7079: 7077: 7074: 7072: 7069: 7067: 7064: 7062: 7059: 7058: 7056: 7054: 7050: 7044: 7041: 7039: 7036: 7034: 7031: 7029: 7026: 7024: 7021: 7019: 7016: 7014: 7011: 7009: 7006: 7004: 7003:Taylor series 7001: 7000: 6998: 6994: 6984: 6981: 6979: 6976: 6974: 6971: 6969: 6966: 6964: 6961: 6959: 6956: 6954: 6951: 6949: 6946: 6944: 6941: 6939: 6936: 6935: 6933: 6929: 6923: 6920: 6918: 6915: 6913: 6910: 6908: 6905: 6904: 6902: 6898: 6895: 6891: 6881: 6878: 6876: 6873: 6871: 6868: 6867: 6865: 6861: 6855: 6852: 6850: 6847: 6845: 6842: 6840: 6837: 6836: 6834: 6830: 6827: 6823: 6817: 6814: 6812: 6809: 6807: 6804: 6803: 6801: 6797: 6792: 6776: 6773: 6772: 6771: 6768: 6766: 6763: 6761: 6758: 6756: 6753: 6751: 6748: 6746: 6743: 6741: 6738: 6736: 6733: 6731: 6728: 6726: 6723: 6722: 6720: 6716: 6709: 6703: 6700: 6698: 6695: 6693: 6692:Powers of two 6690: 6688: 6685: 6683: 6680: 6678: 6677:Square number 6675: 6673: 6670: 6668: 6665: 6663: 6660: 6659: 6657: 6653: 6650: 6648: 6644: 6640: 6636: 6629: 6624: 6622: 6617: 6615: 6610: 6609: 6606: 6590: 6587: 6585: 6582: 6580: 6577: 6575: 6572: 6571: 6569: 6565: 6562: 6560: 6555: 6545: 6542: 6540: 6537: 6535: 6532: 6531: 6529: 6525: 6522: 6520: 6519:4-dimensional 6516: 6506: 6503: 6501: 6498: 6497: 6495: 6493: 6489: 6483: 6480: 6478: 6475: 6473: 6470: 6468: 6465: 6463: 6460: 6459: 6457: 6455: 6451: 6445: 6442: 6440: 6437: 6435: 6432: 6430: 6427: 6425: 6422: 6421: 6419: 6417: 6413: 6410: 6408: 6407:3-dimensional 6404: 6394: 6391: 6389: 6386: 6384: 6381: 6379: 6376: 6374: 6371: 6369: 6366: 6364: 6361: 6359: 6356: 6354: 6351: 6350: 6348: 6346: 6342: 6336: 6333: 6331: 6328: 6326: 6323: 6321: 6318: 6316: 6313: 6311: 6308: 6306: 6303: 6301: 6298: 6296: 6293: 6292: 6290: 6288: 6284: 6281: 6279: 6278:2-dimensional 6275: 6271: 6264: 6259: 6257: 6252: 6250: 6245: 6244: 6241: 6234: 6230: 6227: 6222: 6221: 6216: 6213: 6208: 6206: 6202: 6199: 6197: 6193: 6190: 6186: 6182: 6181: 6176: 6172: 6171: 6167: 6160: 6156: 6152: 6146: 6142: 6138: 6134: 6127: 6124: 6120: 6114: 6111: 6106: 6105: 6100: 6096: 6090: 6088: 6084: 6079: 6075: 6071: 6065: 6061: 6057: 6053: 6052: 6044: 6041: 6036: 6034:9781421417288 6030: 6026: 6022: 6018: 6017: 6009: 6006: 5993: 5986: 5983: 5971: 5967: 5963: 5959: 5955: 5951: 5947: 5940: 5937: 5931: 5926: 5919: 5916: 5911: 5907: 5903: 5899: 5895: 5891: 5887: 5883: 5876: 5873: 5870: 5865: 5862: 5859: 5854: 5851: 5846: 5842: 5838: 5834: 5830: 5826: 5822: 5819:(in German). 5818: 5811: 5808: 5798: 5795: 5790: 5783: 5780: 5767: 5763: 5759: 5753: 5750: 5746: 5740: 5737: 5731: 5728: 5716:. Mathcentral 5715: 5708: 5705: 5694:on 2015-04-02 5693: 5689: 5685: 5678: 5675: 5670: 5664: 5660: 5659: 5654: 5648: 5645: 5640: 5636: 5630: 5627: 5621: 5616: 5613: 5610: 5607: 5605: 5602: 5601: 5597: 5595: 5592: 5586: 5581: 5577: 5569: 5567: 5547: 5542: 5534: 5529: 5514: 5510: 5507: 5502: 5499: 5496: 5493: 5485: 5482: 5473: 5468: 5464: 5458: 5445: 5437: 5430: 5427: 5424: 5421: 5418: 5415: 5412: 5409: 5406: 5403: 5400: 5397: 5394: 5391: 5388: 5385: 5382: 5379: 5376: 5373: 5370: 5367: 5365: 5359: 5358: 5354: 5351: 5348: 5345: 5342: 5339: 5336: 5333: 5330: 5327: 5324: 5321: 5318: 5315: 5312: 5309: 5306: 5303: 5300: 5297: 5294: 5291: 5289: 5286: 5285: 5281: 5278: 5275: 5272: 5269: 5266: 5263: 5260: 5257: 5254: 5251: 5248: 5245: 5242: 5239: 5236: 5233: 5230: 5227: 5224: 5221: 5218: 5215: 5214: 5208: 5202: 5200: 5196: 5192: 5109: 5103: 5097: 5091: 5085: 5074: 5070: 5062: 5058: 5050: 5046: 5039: 5032: 5028: 5023: 5019: 5014: 5009: 5005: 4999: 4994: 4989: 4984: 4980: 4974: 4969: 4961: 4957: 4953: 4948: 4941: 4939: 4922: 4917: 4912: 4907: 4902: 4894: 4889: 4884: 4879: 4874: 4869: 4861: 4856: 4851: 4846: 4833: 4831: 4813: 4809: 4805: 4800: 4796: 4792: 4787: 4783: 4774: 4753: 4749: 4745: 4738: 4714: 4711: 4708: 4702: 4696: 4693: 4690: 4677: 4671: 4668: 4663: 4656: 4639: 4636: 4633: 4627: 4621: 4618: 4613: 4607: 4604: 4601: 4595: 4589: 4586: 4581: 4574: 4558: 4554: 4550: 4545: 4542: 4539: 4535: 4527: 4526: 4525: 4522: 4520: 4516: 4511: 4509: 4505: 4501: 4497: 4495: 4491: 4482: 4480: 4473: 4465: 4459: 4445: 4440: 4437: 4434: 4430: 4424: 4421: 4418: 4414: 4410: 4405: 4401: 4395: 4391: 4387: 4382: 4379: 4375: 4354: 4351: 4348: 4343: 4339: 4335: 4330: 4326: 4322: 4317: 4314: 4311: 4307: 4297: 4284: 4281: 4272: 4269: 4266: 4260: 4256: 4244: 4241: 4238: 4234: 4225: 4220: 4207: 4204: 4198: 4195: 4190: 4186: 4181: 4169: 4166: 4163: 4159: 4155: 4152: 4145: 4141: 4138: 4133: 4129: 4122: 4110: 4107: 4104: 4100: 4091: 4086: 4085:, and so on. 4081: 4076: 4068: 4063: 4055: 4050: 4042: 4037: 4030: 4026: 4020: 4013: 4005: 3997: 3989: 3981: 3973: 3965: 3958: 3952: 3945: 3940: 3936: 3929: 3912: 3904: 3898: 3892: 3888: 3882: 3876: 3873: 3868: 3865: 3862: 3859: 3856: 3853: 3850: 3847: 3844: 3841: 3838: 3835: 3832: 3827: 3825: 3821: 3816: 3813: 3810: 3808: 3803: 3779: 3775: 3770: 3766: 3761: 3754: 3751: 3746: 3742: 3733: 3729: 3722: 3717: 3714: 3711: 3707: 3701: 3697: 3688: 3683: 3676: 3672: 3665: 3659: 3653: 3645: 3643: 3635: 3630: 3626: 3622: 3618: 3614: 3610: 3605: 3601: 3580: 3576: 3573: 3570: 3567: 3562: 3558: 3545: 3540: 3536: 3528: 3524: 3518: 3515: 3510: 3506: 3501: 3493: 3489: 3483: 3480: 3475: 3471: 3466: 3462: 3455: 3452: 3449: 3445: 3439: 3436: 3431: 3428: 3425: 3421: 3416: 3408: 3404: 3398: 3395: 3390: 3387: 3384: 3380: 3375: 3366: 3350: 3339: 3335: 3332: 3327: 3323: 3310: 3305: 3301: 3293: 3289: 3283: 3280: 3275: 3271: 3266: 3258: 3254: 3248: 3245: 3240: 3236: 3231: 3202: 3198: 3195: 3190: 3186: 3173: 3168: 3164: 3156: 3152: 3146: 3143: 3138: 3134: 3129: 3119: 3117: 3112: 3109: 3103: 3090: 3087: 3082: 3079: 3076: 3072: 3068: 3065: 3060: 3056: 3052: 3043: 3037: 3032: 3028: 3024: 3018: 3010: 3003: 2998: 2997:-gonal number 2995: 2988: 2982: 2969: 2964: 2957: 2954: 2951: 2942: 2939: 2936: 2930: 2924: 2919: 2912: 2909: 2906: 2900: 2892: 2887: 2884: 2881: 2877: 2873: 2868: 2864: 2858: 2853: 2850: 2847: 2843: 2834: 2829: 2819: 2806: 2801: 2796: 2792: 2787: 2782: 2779: 2776: 2772: 2767: 2762: 2757: 2753: 2747: 2742: 2739: 2736: 2732: 2722: 2717: 2714: 2704:cube numbers. 2702: 2696: 2690: 2686: 2673: 2670: 2665: 2661: 2640: 2637: 2632: 2628: 2607: 2604: 2599: 2596: 2593: 2589: 2585: 2580: 2577: 2574: 2570: 2566: 2563: 2558: 2554: 2545: 2542: 2538: 2525: 2522: 2517: 2513: 2491: 2487: 2484: 2479: 2475: 2471: 2467: 2461: 2457: 2453: 2450: 2445: 2442: 2439: 2435: 2425: 2423: 2422:pronic number 2419: 2412: 2406: 2400: 2397: 2384: 2379: 2369: 2366: 2363: 2359: 2355: 2350: 2346: 2339: 2334: 2330: 2326: 2322: 2316: 2313: 2308: 2303: 2298: 2294: 2287: 2283: 2279: 2273: 2270: 2265: 2260: 2255: 2251: 2244: 2240: 2236: 2230: 2220: 2215: 2211: 2208: 2205: 2201: 2192: 2189: 2186: 2180: 2175: 2170: 2165: 2161: 2158: 2155: 2151: 2143: 2139: 2135: 2129: 2126: 2121: 2116: 2111: 2107: 2100: 2096: 2091: 2088: 2085: 2081: 2077: 2072: 2068: 2057: 2051: 2049: 2036: 2031: 2028: 2023: 2016: 2012: 2006: 2002: 1988: 1975: 1970: 1957: 1954: 1949: 1945: 1938: 1932: 1929: 1926: 1920: 1917: 1912: 1909: 1906: 1902: 1898: 1893: 1889: 1876: 1865: 1862: 1851: 1848: 1843: 1840: 1837: 1833: 1829: 1826: 1821: 1817: 1808: 1802: 1800: 1799: 1793: 1780: 1777: 1774: 1771: 1768: 1765: 1762: 1759: 1756: 1753: 1750: 1747: 1744: 1741: 1738: 1735: 1732: 1729: 1726: 1723: 1720: 1717: 1714: 1711: 1703: 1701: 1700: 1696:For example, 1694: 1692: 1691: 1686: 1685: 1680: 1676: 1672: 1667: 1664: 1659: 1655: 1650: 1642: 1638: 1632: 1625: 1620: 1614: 1610: 1601: 1597: 1593: 1591: 1589: 1585: 1581: 1575: 1559: 1550: 1545: 1531: 1511: 1491: 1471: 1451: 1448: 1445: 1425: 1416: 1399: 1394: 1387: 1384: 1381: 1372: 1369: 1366: 1357: 1355: 1345: 1341: 1338: 1335: 1332: 1329: 1324: 1320: 1313: 1311: 1301: 1297: 1294: 1291: 1288: 1285: 1282: 1279: 1274: 1270: 1263: 1261: 1251: 1247: 1244: 1241: 1238: 1235: 1229: 1226: 1223: 1217: 1211: 1209: 1201: 1198: 1195: 1192: 1187: 1180: 1177: 1174: 1168: 1162: 1160: 1152: 1149: 1146: 1140: 1137: 1132: 1127: 1124: 1121: 1117: 1104: 1090: 1087: 1084: 1062: 1055: 1052: 1049: 1043: 1037: 1034: 1029: 1024: 1021: 1018: 1014: 1010: 1005: 1001: 980: 971: 958: 955: 950: 947: 942: 937: 930: 927: 924: 918: 912: 909: 904: 899: 896: 893: 889: 885: 880: 876: 867: 853: 845: 838: 821: 818: 813: 806: 803: 800: 794: 788: 783: 779: 758: 755: 749: 746: 743: 737: 734: 729: 725: 721: 713: 697: 693: 670: 663: 660: 657: 651: 645: 640: 636: 612: 609: 606: 600: 597: 575: 571: 562: 546: 542: 535: 532: 529: 523: 503: 494: 491: 484: 479: 454: 450: 447: 444: 399: 395: 392: 389: 377: 375: 365: 358: 355: 352: 346: 340: 335: 324: 321: 318: 308: 305: 300: 296: 289: 287: 279: 276: 273: 270: 267: 264: 261: 258: 255: 250: 245: 242: 239: 235: 231: 229: 222: 218: 204: 197: 187: 177: 168: 159: 150: 141: 132: 127: 120: 118: 116: 111: 102: 100: 96: 91: 86: 82: 76: 70: 65: 61: 57: 53: 49: 45: 36: 26: 21: 8771:Transposable 8635:Narcissistic 8542:Digital root 8462:Super-Poulet 8422:Jordan–Pólya 8371:prime factor 8276:Noncototient 8243:Almost prime 8225:Superperfect 8200:Refactorable 8195:Quasiperfect 8170:Hyperperfect 8011:Pseudoprimes 7982:Wall–Sun–Sun 7917:Ordered Bell 7887:Fuss–Catalan 7799:non-centered 7749:Dodecahedral 7726:non-centered 7619: 7612:non-centered 7514:Wolstenholme 7259:× 2 ± 1 7256: 7255:Of the form 7222:Eighth power 7202:Fourth power 7008:Power series 6769: 6750:Lucas number 6702:Powers of 10 6682:Cubic number 6567:non-centered 6527:non-centered 6462:Cube numbers 6454:non-centered 6352: 6345:non-centered 6335:Star numbers 6232: 6218: 6205:cut-the-knot 6196:cut-the-knot 6178: 6132: 6126: 6118: 6113: 6103: 6050: 6043: 6015: 6008: 5996:. Retrieved 5985: 5973:. Retrieved 5953: 5949: 5939: 5918: 5885: 5881: 5875: 5864: 5853: 5820: 5816: 5806: 5797: 5788: 5782: 5770:. Retrieved 5766:the original 5761: 5752: 5739: 5730: 5718:. Retrieved 5707: 5696:. Retrieved 5692:the original 5687: 5677: 5657: 5647: 5638: 5629: 5590: 5584: 5576:Donald Knuth 5573: 5545: 5530: 5471: 5466: 5462: 5456: 5441: 5360: 5287: 5193: 5107: 5101: 5095: 5089: 5083: 5072: 5068: 5060: 5056: 5048: 5044: 5037: 5030: 5026: 5018:depreciation 5015: 5007: 5003: 4997: 4990: 4982: 4978: 4972: 4965: 4959: 4955: 4951: 4942:Applications 4834: 4770: 4523: 4512: 4498: 4483: 4463: 4460: 4298: 4221: 4087: 4079: 4074: 4066: 4061: 4053: 4048: 4040: 4035: 4028: 4024: 4022:is equal to 4018: 4011: 4003: 3995: 3987: 3979: 3971: 3963: 3956: 3950: 3943: 3938: 3934: 3927: 3925:. Note that 3910: 3902: 3896: 3890: 3886: 3880: 3877: 3874: 3871: 3866: 3863: 3860: 3857: 3854: 3851: 3848: 3845: 3842: 3839: 3836: 3833: 3830: 3824:digital root 3817: 3814: 3811: 3798: 3684: 3681: 3657: 3639: 3620: 3616: 3612: 3608: 3120: 3113: 3107: 3104: 3041: 3039:th centered 3035: 3016: 3008: 3001: 2993: 2986: 2983: 2827: 2820: 2720: 2712: 2707: 2700: 2694: 2540: 2539: 2426: 2415: 2398: 2058: 2055: 1971: 1803: 1797: 1796: 1794: 1704: 1698: 1697: 1695: 1689: 1688: 1683: 1682: 1681:and denoted 1675:Donald Knuth 1670: 1668: 1662: 1657: 1648: 1640: 1636: 1630: 1623: 1618: 1612: 1608: 1605: 1592: 1580:Pythagoreans 1573: 1557: 1546: 1417: 1105: 972: 868: 841: 561:visual proof 495: 489: 482: 426: 202: 148: 106: 89: 80: 74: 68: 64:cube numbers 47: 43: 41: 24: 8792:Extravagant 8787:Equidigital 8742:permutation 8701:Palindromic 8675:Automorphic 8573:Sum-product 8552:Sum-product 8507:Persistence 8402:Erdős–Woods 8324:Untouchable 8205:Semiperfect 8155:Hemiperfect 7816:Tesseractic 7754:Icosahedral 7734:Tetrahedral 7665:Dodecagonal 7366:Recursively 7237:Prime power 7212:Sixth power 7207:Fifth power 7187:Power of 10 7145:Classes of 6875:Conditional 6863:Convergence 6854:Telescoping 6839:Alternating 6755:Pell number 6559:dimensional 5639:Math Is Fun 5444:square root 4993:group stage 4486:2 − 1 4090:reciprocals 3855:45 = 9 × 5 3852:36 = 9 × 4 3685:Every even 3363:which uses 1617:solves the 9053:Categories 9004:Graphemics 8877:Pernicious 8731:Undulating 8706:Pandigital 8680:Trimorphic 8281:Nontotient 8130:Arithmetic 7744:Octahedral 7645:Heptagonal 7635:Pentagonal 7620:Triangular 7461:Sierpiński 7383:Jacobsthal 7182:Power of 3 7177:Power of 2 6900:Convergent 6844:Convergent 5998:2024-04-14 5930:1601.06378 5823:: 89–100. 5772:12 January 5698:2014-04-16 5622:References 5588:? for the 5580:factorials 5460:such that 5216:Max. pips 5195:Board game 4830:digit sums 3829:0 = 9 × 0 2708:Also, the 1699:10 termial 1634:people is 107:(sequence 87:from 1 to 9084:Triangles 8761:Parasitic 8610:Factorion 8537:Digit sum 8529:Digit sum 8347:Fortunate 8334:Primorial 8248:Semiprime 8185:Practical 8150:Descartes 8145:Deficient 8135:Betrothed 7977:Wieferich 7806:Pentatope 7769:pyramidal 7660:Decagonal 7655:Nonagonal 7650:Octagonal 7640:Hexagonal 7499:Practical 7446:Congruent 7378:Fibonacci 7342:Loeschian 6931:Divergent 6849:Divergent 6711:Advanced 6687:Factorial 6635:Sequences 6492:pyramidal 6220:MathWorld 6185:EMS Press 6078:198342061 5910:122221070 5902:1382-4090 5845:125426184 5837:1432-1815 5615:Tetractys 5508:− 5010:− 1 4985:− 1 4694:− 4605:− 4543:− 4438:− 4422:− 4250:∞ 4235:∑ 4175:∞ 4160:∑ 4116:∞ 4101:∑ 3715:− 3574:− 3502:∑ 3467:∑ 3463:… 3453:− 3429:− 3417:∑ 3388:− 3376:∑ 3267:∑ 3232:∑ 3130:∑ 3080:− 2878:∑ 2844:∑ 2773:∑ 2733:∑ 2597:− 2586:− 2578:− 2367:− 2356:− 2309:− 2209:− 2190:− 2159:− 2089:− 1995:∞ 1992:→ 1930:− 1910:− 1841:− 1654:factorial 1118:∑ 1077:. Adding 1015:∑ 890:∑ 712:follows: 601:× 274:⋯ 236:∑ 196:7-simplex 186:6-simplex 176:5-simplex 8833:Friedman 8766:Primeval 8711:Repdigit 8668:-related 8615:Kaprekar 8589:Meertens 8512:Additive 8499:dynamics 8407:Friendly 8319:Sociable 8309:Amicable 8120:Abundant 8100:dynamics 7922:Schröder 7912:Narayana 7882:Eulerian 7872:Delannoy 7867:Dedekind 7688:centered 7554:centered 7441:Amenable 7398:Narayana 7388:Leonardo 7284:Mersenne 7232:Powerful 7172:Achilles 7104:Category 6870:Absolute 6416:centered 6287:centered 6159:53079729 6101:(1810), 5975:25 April 5720:28 March 5658:Calculus 5655:(2008). 5598:See also 5081:, where 5035:, where 3942:+ 1 = (2 2999:and the 1658:products 1588:Computus 95:sequence 9006:related 8970:related 8934:related 8932:Sorting 8817:Vampire 8802:Harshad 8744:related 8716:Repunit 8630:Lychrel 8605:Dudeney 8457:Størmer 8452:Sphenic 8437:Regular 8375:divisor 8314:Perfect 8210:Sublime 8180:Perfect 7907:Motzkin 7862:Catalan 7403:Padovan 7337:Leyland 7332:Idoneal 7327:Hilbert 7299:Woodall 6880:Uniform 6557:Higher 6187:, 2001 5970:3621134 5562:is the 5189:⁠ 5177:⁠ 5173:⁠ 5161:⁠ 5157:⁠ 5145:⁠ 5141:⁠ 5129:⁠ 5125:⁠ 5113:⁠ 5078:⁠ 5053:⁠ 4472:ΕΥΡΗΚΑ! 3968:) are: 3922:⁠ 3907:⁠ 3820:base 10 1972:In the 1568:⁠ 1554:⁠ 198:numbers 188:numbers 178:numbers 121:Formula 113:in the 110:A000217 8872:Odious 8797:Frugal 8751:Cyclic 8740:Digit- 8447:Smooth 8432:Pronic 8392:Cyclic 8369:Other 8342:Euclid 7992:Wilson 7966:Primes 7625:Square 7494:Polite 7456:Riesel 7451:Knödel 7413:Perrin 7294:Thabit 7279:Fermat 7269:Cullen 7192:Square 7160:Powers 6832:Series 6639:series 6157:  6147:  6076:  6066:  6031:  5968:  5908:  5900:  5843:  5835:  5665:  5207:domino 3954:given 3822:, the 3796:where 3105:where 3033:; the 1942:  1886:  1883:  1880:  1584:Dicuil 427:where 194:  192:  184:  182:  174:  172:  165:  163:  156:  154:  147:  145:  138:  136:  93:. The 66:. The 8913:Prime 8908:Lucky 8897:sieve 8826:Other 8812:Smith 8692:Digit 8650:Happy 8625:Keith 8598:Other 8442:Rough 8412:Giuga 7877:Euler 7739:Cubic 7393:Lucas 7289:Proth 6775:array 6655:Basic 6155:S2CID 6074:S2CID 5966:JSTOR 5925:arXiv 5906:S2CID 5841:S2CID 5813:(PDF) 5804:"Die 4492:(see 3805:is a 2620:with 2505:with 1974:limit 1673:" by 101:, is 8867:Evil 8547:Self 8497:and 8387:Blum 8098:and 7902:Lobb 7857:Cake 7852:Bell 7602:Star 7509:Ulam 7408:Pell 7197:Cube 6715:list 6637:and 6145:ISBN 6064:ISBN 6029:ISBN 5977:2024 5898:ISSN 5833:ISSN 5774:2022 5722:2015 5663:ISBN 5431:253 5422:190 5419:161 5413:136 5410:120 5051:) × 4490:4095 4367:and 4014:+ 21 4006:+ 15 3998:+ 10 3946:+ 1) 3019:− 1) 3011:+ 1) 2653:and 115:OEIS 62:and 8985:Ban 8373:or 7892:Lah 6203:at 6194:at 6137:doi 6056:doi 6021:doi 5958:doi 5890:doi 5825:doi 5554:of 5548:+ 1 5446:of 5428:231 5425:210 5416:153 5407:105 5404:91 5401:78 5395:55 5392:45 5386:28 5383:21 5355:22 5346:19 5343:18 5337:16 5334:15 5328:13 5325:12 5319:10 5282:21 5273:18 5270:17 5264:15 5261:14 5255:12 5252:11 4970:of 4828:as 4496:). 4488:is 4082:+ 4 4069:+ 3 4056:+ 2 4043:+ 1 4010:169 4002:121 3990:+ 6 3982:+ 3 3974:+ 1 3966:+ 0 3913:− 1 3878:If 3869:... 3818:In 3619:th 3611:th 3005:th 2990:th 2831:th 2541:All 1985:lim 1677:'s 1666:. 1626:+ 1 1576:+ 1 485:+ 1 46:or 9055:: 6217:. 6183:, 6177:, 6153:, 6143:, 6097:; 6086:^ 6072:. 6062:. 6054:. 6027:. 5964:. 5954:86 5952:. 5948:. 5904:. 5896:. 5884:. 5839:. 5831:. 5821:66 5815:. 5760:. 5686:. 5637:. 5475:: 5470:= 5398:66 5389:36 5380:15 5377:10 5352:21 5349:20 5340:17 5331:14 5322:11 5316:9 5310:7 5307:6 5279:20 5276:19 5267:16 5258:13 5249:10 5246:9 5243:8 5237:6 5234:5 5186:10 5180:10 5170:10 5154:10 5138:10 5122:10 5059:− 5047:− 4966:A 4832:: 4521:. 4481:. 4285:1. 4226:: 4208:2. 4072:, 4059:, 4046:, 4008:, 4000:, 3994:81 3992:, 3986:49 3984:, 3978:25 3976:, 3905:= 3889:+ 3887:ax 3644:. 3118:. 2835:: 2674:1. 2567:34 2526:1. 2424:. 1958:0. 1809:: 1801:. 1781:55 1775:10 1712:10 1693:) 1690:n! 1684:n? 1643:−1 1504:, 993:, 959:1. 866:: 822:10 759:20 133:. 117:) 42:A 7257:a 7138:e 7131:t 7124:v 6717:) 6713:( 6627:e 6620:t 6613:v 6262:e 6255:t 6248:v 6223:. 6139:: 6080:. 6058:: 6037:. 6023:: 6001:. 5979:. 5960:: 5933:. 5927:: 5912:. 5892:: 5886:7 5847:. 5827:: 5807:k 5776:. 5747:. 5724:. 5701:. 5671:. 5641:. 5591:n 5585:n 5564:n 5560:x 5556:x 5552:n 5546:x 5544:8 5537:x 5515:2 5511:1 5503:1 5500:+ 5497:x 5494:8 5486:= 5483:n 5472:x 5467:n 5463:T 5457:n 5452:x 5448:x 5374:6 5371:3 5368:1 5363:n 5361:T 5313:8 5304:5 5301:4 5298:3 5295:2 5292:1 5288:n 5240:7 5231:4 5228:3 5225:2 5222:1 5219:0 5183:/ 5167:/ 5164:1 5151:/ 5148:2 5135:/ 5132:3 5119:/ 5116:4 5108:n 5102:y 5096:n 5090:s 5084:b 5073:n 5069:T 5065:/ 5061:y 5057:n 5049:s 5045:b 5043:( 5038:n 5031:n 5027:T 5008:n 5004:T 4998:n 4983:n 4979:T 4973:n 4960:n 4956:n 4952:p 4923:5 4918:5 4913:5 4908:5 4903:5 4895:5 4890:4 4885:3 4880:2 4875:1 4870:+ 4862:1 4857:2 4852:3 4847:4 4814:2 4810:5 4806:= 4801:5 4797:T 4793:+ 4788:4 4784:T 4754:2 4750:n 4746:= 4723:) 4718:) 4715:1 4712:+ 4709:n 4706:( 4703:+ 4700:) 4697:1 4691:n 4688:( 4683:( 4678:n 4672:2 4669:1 4664:= 4643:) 4640:1 4637:+ 4634:n 4631:( 4628:n 4622:2 4619:1 4614:+ 4611:) 4608:1 4602:n 4599:( 4596:n 4590:2 4587:1 4582:= 4559:n 4555:T 4551:+ 4546:1 4540:n 4536:T 4467:0 4464:T 4446:, 4441:1 4435:b 4431:T 4425:1 4419:a 4415:T 4411:+ 4406:b 4402:T 4396:a 4392:T 4388:= 4383:b 4380:a 4376:T 4355:b 4352:a 4349:+ 4344:b 4340:T 4336:+ 4331:a 4327:T 4323:= 4318:b 4315:+ 4312:a 4308:T 4282:= 4276:) 4273:1 4270:+ 4267:n 4264:( 4261:n 4257:1 4245:1 4242:= 4239:n 4205:= 4199:n 4196:+ 4191:2 4187:n 4182:1 4170:1 4167:= 4164:n 4156:2 4153:= 4146:2 4142:n 4139:+ 4134:2 4130:n 4123:1 4111:1 4108:= 4105:n 4080:n 4078:9 4075:T 4067:n 4065:7 4062:T 4054:n 4052:5 4049:T 4041:n 4039:3 4036:T 4029:n 4025:T 4019:x 4012:x 4004:x 3996:x 3988:x 3980:x 3972:x 3970:9 3964:x 3962:1 3957:a 3951:b 3944:n 3939:n 3935:T 3933:8 3928:b 3919:8 3916:/ 3911:a 3903:b 3897:a 3891:b 3881:x 3801:p 3799:M 3780:p 3776:M 3771:T 3767:= 3762:2 3758:) 3755:1 3752:+ 3747:p 3743:M 3739:( 3734:p 3730:M 3723:= 3718:1 3712:p 3708:2 3702:p 3698:M 3621:n 3617:k 3613:k 3609:n 3586:) 3581:k 3577:1 3571:k 3568:+ 3563:k 3559:n 3552:( 3546:= 3541:1 3537:n 3529:2 3525:n 3519:1 3516:= 3511:1 3507:n 3494:3 3490:n 3484:1 3481:= 3476:2 3472:n 3456:1 3450:k 3446:n 3440:1 3437:= 3432:2 3426:k 3422:n 3409:k 3405:n 3399:1 3396:= 3391:1 3385:k 3381:n 3351:, 3345:) 3340:3 3336:2 3333:+ 3328:3 3324:n 3317:( 3311:= 3306:1 3302:n 3294:2 3290:n 3284:1 3281:= 3276:1 3272:n 3259:3 3255:n 3249:1 3246:= 3241:2 3237:n 3208:) 3203:2 3199:1 3196:+ 3191:2 3187:n 3180:( 3174:= 3169:1 3165:n 3157:2 3153:n 3147:1 3144:= 3139:1 3135:n 3108:T 3091:1 3088:+ 3083:1 3077:n 3073:T 3069:k 3066:= 3061:n 3057:k 3053:C 3042:k 3036:n 3017:n 3015:( 3009:m 3007:( 3002:n 2994:m 2987:n 2970:. 2965:6 2961:) 2958:2 2955:+ 2952:n 2949:( 2946:) 2943:1 2940:+ 2937:n 2934:( 2931:n 2925:= 2920:2 2916:) 2913:1 2910:+ 2907:k 2904:( 2901:k 2893:n 2888:1 2885:= 2882:k 2874:= 2869:k 2865:T 2859:n 2854:1 2851:= 2848:k 2828:n 2823:n 2807:. 2802:2 2797:) 2793:k 2788:n 2783:1 2780:= 2777:k 2768:( 2763:= 2758:3 2754:k 2748:n 2743:1 2740:= 2737:k 2721:n 2713:n 2701:n 2695:n 2671:= 2666:1 2662:S 2641:0 2638:= 2633:0 2629:S 2608:2 2605:+ 2600:2 2594:n 2590:S 2581:1 2575:n 2571:S 2564:= 2559:n 2555:S 2523:= 2518:1 2514:S 2492:) 2488:1 2485:+ 2480:n 2476:S 2472:8 2468:( 2462:n 2458:S 2454:4 2451:= 2446:1 2443:+ 2440:n 2436:S 2385:. 2380:2 2376:) 2370:1 2364:n 2360:T 2351:n 2347:T 2343:( 2340:= 2335:2 2331:n 2327:= 2323:) 2317:2 2314:n 2304:2 2299:2 2295:n 2288:( 2284:+ 2280:) 2274:2 2271:n 2266:+ 2261:2 2256:2 2252:n 2245:( 2241:= 2237:) 2231:2 2221:2 2216:) 2212:1 2206:n 2202:( 2193:1 2187:n 2181:+ 2176:2 2171:2 2166:) 2162:1 2156:n 2152:( 2144:( 2140:+ 2136:) 2130:2 2127:n 2122:+ 2117:2 2112:2 2108:n 2101:( 2097:= 2092:1 2086:n 2082:T 2078:+ 2073:n 2069:T 2037:. 2032:3 2029:1 2024:= 2017:n 2013:L 2007:n 2003:T 1989:n 1955:= 1950:1 1946:L 1939:, 1936:) 1933:1 1927:n 1924:( 1921:3 1918:+ 1913:1 1907:n 1903:L 1899:= 1894:n 1890:L 1877:; 1871:) 1866:2 1863:n 1858:( 1852:3 1849:= 1844:1 1838:n 1834:T 1830:3 1827:= 1822:n 1818:L 1778:= 1772:+ 1769:9 1766:+ 1763:8 1760:+ 1757:7 1754:+ 1751:6 1748:+ 1745:5 1742:+ 1739:4 1736:+ 1733:3 1730:+ 1727:2 1724:+ 1721:1 1718:= 1715:? 1663:n 1649:T 1641:n 1637:T 1631:n 1624:n 1613:n 1609:T 1574:n 1565:2 1562:/ 1558:n 1532:n 1512:3 1492:2 1472:1 1452:1 1449:+ 1446:m 1426:m 1400:, 1395:2 1391:) 1388:2 1385:+ 1382:m 1379:( 1376:) 1373:1 1370:+ 1367:m 1364:( 1358:= 1346:2 1342:2 1339:+ 1336:m 1333:3 1330:+ 1325:2 1321:m 1314:= 1302:2 1298:2 1295:+ 1292:m 1289:2 1286:+ 1283:m 1280:+ 1275:2 1271:m 1264:= 1252:2 1248:2 1245:+ 1242:m 1239:2 1236:+ 1233:) 1230:1 1227:+ 1224:m 1221:( 1218:m 1212:= 1202:1 1199:+ 1196:m 1193:+ 1188:2 1184:) 1181:1 1178:+ 1175:m 1172:( 1169:m 1163:= 1156:) 1153:1 1150:+ 1147:m 1144:( 1141:+ 1138:k 1133:m 1128:1 1125:= 1122:k 1091:1 1088:+ 1085:m 1063:2 1059:) 1056:1 1053:+ 1050:m 1047:( 1044:m 1038:= 1035:k 1030:m 1025:1 1022:= 1019:k 1011:= 1006:m 1002:T 981:m 956:= 951:2 948:2 943:= 938:2 934:) 931:1 928:+ 925:1 922:( 919:1 913:= 910:k 905:1 900:1 897:= 894:k 886:= 881:1 877:T 854:1 819:= 814:2 810:) 807:1 804:+ 801:4 798:( 795:4 789:= 784:4 780:T 756:= 753:) 750:1 747:+ 744:4 741:( 738:4 735:= 730:4 726:T 722:2 698:4 694:T 671:2 667:) 664:1 661:+ 658:n 655:( 652:n 646:= 641:n 637:T 616:) 613:1 610:+ 607:n 604:( 598:n 576:n 572:T 547:2 543:/ 539:) 536:1 533:+ 530:n 527:( 524:n 504:n 490:n 483:n 460:) 455:2 451:1 448:+ 445:n 439:( 405:) 400:2 396:1 393:+ 390:n 384:( 378:= 366:2 362:) 359:1 356:+ 353:n 350:( 347:n 341:= 336:2 328:) 325:1 322:+ 319:n 316:( 309:n 306:+ 301:2 297:n 290:= 280:n 277:+ 271:+ 268:2 265:+ 262:1 259:= 256:k 251:n 246:1 243:= 240:k 232:= 223:n 219:T 90:n 81:n 75:n 69:n 30:) 28:0 25:T

Index



equilateral triangle
figurate number
square numbers
cube numbers
natural numbers
sequence
0th triangular number
A000217
OEIS

Pascal's triangle
Natural numbers
Tetrahedral numbers
Pentatope numbers
5-simplex
6-simplex
7-simplex
binomial coefficient
visual proof

mathematical induction
Carl Friedrich Gauss
Pythagoreans
Dicuil
Computus

Proof without words
factorial

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