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Greedy algorithm for Egyptian fractions

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As each expansion step reduces the numerator of the remaining fraction to be expanded, this method always terminates with a finite expansion; however, compared to ancient Egyptian expansions or to more modern methods, this method may produce expansions that are quite long, with large denominators.
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based on the greedy method. Their algorithm computes the greedy expansion of a root; at each step in this expansion it maintains an auxiliary polynomial that has as its root the remaining fraction to be expanded. Consider as an example applying this method to find the greedy expansion of the
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for a more detailed listing of these methods. As Salzer (1948) details, the greedy method, and extensions of it for the approximation of irrational numbers, have been rediscovered several times by modern mathematicians, earliest and most notably by
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However, it may be difficult to determine whether an algorithm of this type can always succeed in finding a finite expansion. In particular, it is unknown whether the odd greedy expansion terminates with a finite expansion for all fractions
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Fibonacci actually lists several different methods for constructing Egyptian fraction representations. He includes the greedy method as a last resort for situations when several simpler methods fail; see
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In general, if one wants an Egyptian fraction expansion in which the denominators are constrained in some way, it is possible to define a greedy algorithm in which at each step one chooses the expansion
362: 2284: 1001: 744:{\displaystyle {\frac {5}{121}}={\frac {1}{25}}+{\frac {1}{757}}+{\frac {1}{763\,309}}+{\frac {1}{873\,960\,180\,913}}+{\frac {1}{1\,527\,612\,795\,642\,093\,418\,846\,225}},} 754: 2564: 2624: 248: 2644: 2584: 2535: 204: 172: 2390:
The length, minimum denominator, and maximum denominator of the greedy expansion for all fractions with small numerators and denominators can be found in the
147:) A closely related expansion method that produces closer approximations at each step by allowing some unit fractions in the sum to be negative dates back to 1744:{\displaystyle 1,{\frac {2}{3}},{\frac {3}{7}},{\frac {4}{17}},{\frac {5}{31}},{\frac {6}{109}},{\frac {7}{253}},{\frac {8}{97}},{\frac {9}{271}},\dots } 2448: 352:{\displaystyle {\frac {x}{y}}={\frac {1}{\left\lceil {\frac {y}{x}}\right\rceil }}+{\frac {(-y){\bmod {x}}}{y\left\lceil {\frac {y}{x}}\right\rceil }}} 2416: 2406: 2396: 2391: 2379: 1758: 934: 3179: 3174: 3169: 2724:
Cahen, E. (1891), "Note sur un développement des quantités numériques, qui presente quelque analogie avec celui en fractions continues",
942:) can be viewed as generated by an infinite greedy expansion of this type for the number 1, where at each step we choose the denominator 3098: 2913: 3034: 1547: 839:. The greedy method leads to an expansion with ten terms, the last of which has over 500 digits in its denominator; however, 2867: 2828: 2743: 1428:{\displaystyle {\frac {(-y){\bmod {x}}}{y\left\lceil {\frac {y}{x}}\right\rceil }}={\frac {2}{\,{\frac {y(y+2)}{3}}\,}}} 126:(Fibonacci). It is called a greedy algorithm because at each step the algorithm chooses greedily the largest possible 3214: 2018:
and 1, and the first term in its greedy expansion (the second term in the greedy expansion for the golden ratio) is
3219: 3184: 2365:{\displaystyle \varphi ={\frac {1}{1}}+{\frac {1}{2}}+{\frac {1}{9}}+{\frac {1}{145}}+{\frac {1}{37986}}+\cdots } 1101:
describes an application of these closest-approximation results in lower-bounding the number of divisors of a
447:{\displaystyle {\frac {7}{15}}={\frac {1}{3}}+{\frac {2}{15}}={\frac {1}{3}}+{\frac {1}{8}}+{\frac {1}{120}}.} 3091: 2792: 929: 1777: 140: 116:, but the first published systematic method for constructing such expansions was described in 1202 in the 2646:
is odd, although it is possible to find finite odd expansions for these fractions by non-greedy methods.
2738: 1081:-term Egyptian fraction. That is, for example, any Egyptian fraction for a number in the open interval ( 2591: 2586:
is distinct from all previously chosen denominators. Examples of methods defined in this way include
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Continuing this approximation process eventually produces the greedy expansion for the golden ratio,
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Stratemeyer, G. (1930), "Stammbruchentwickelungen für die Quadratwurzel aus einer rationalen Zahl",
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is the remaining fraction after the first step of the greedy expansion, it satisfies the equation
3148: 3084: 3051: 3017: 2988: 2960: 2932: 2884: 2845: 2760: 1070:{\displaystyle {\frac {1}{2}}+{\frac {1}{3}}+{\frac {1}{7}}+{\frac {1}{43}}={\frac {1805}{1806}}} 2865:
Salzer, H. E. (1948), "Further remarks on the approximation of numbers as sums of reciprocals",
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is chosen, among all possible values satisfying the constraints, as small as possible such that
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is the remaining fraction after this step of the greedy expansion, it satisfies the equation
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is the remaining fraction after this step of the greedy expansion, it satisfies the equation
17: 3043: 3009: 2972: 2876: 2837: 2752: 211: 123: 39: 2984: 2896: 2857: 2818: 2784: 3029: 2980: 2892: 2853: 2814: 2780: 2587: 1861:) between 1 and 2. That is, the first term of the greedy expansion of the golden ratio is 454:
in this expansion, the denominator 3 of the first unit fraction is the result of rounding
47: 2601: 225: 2629: 2569: 2520: 1102: 189: 157: 3208: 3021: 2992: 2772: 127: 59: 1807:. The algorithm of Stratemeyer and Salzer performs the following sequence of steps: 2590:, in which each successive denominator must be a multiple of the previous one, and 1782: 1575:
such expansions must be found by methods other than the greedy algorithm, with the
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usually refers, not to this method, but to representation of integers as sums of
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is odd, so the fraction remaining after a single step of the greedy expansion,
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examine the conditions under which the greedy method produces an expansion of
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Salzer, H. E. (1947), "The approximation of numbers as sums of reciprocals",
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leads to an infinite increasing sequence of integers, and the OEIS contains
518:. The denominator of the second unit fraction, 8, is the result of rounding 43: 2805:
Mays, Michael (1987), "A worst case of the Fibonacci–Sylvester expansion",
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requires one term in its greedy expansion; the simplest such fraction is
2937: 1611:-term greedy expansions and that have the smallest possible denominator 3055: 3013: 2976: 2888: 2849: 2764: 3047: 2880: 2841: 2756: 1177:
terms; these can be described in terms of congruence conditions on
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that can be used in any representation of the remaining fraction.
2510:{\displaystyle {\frac {x}{y}}={\frac {1}{d}}+{\frac {xd-y}{yd}},} 994:
terms and forming the corresponding Egyptian fraction, e.g. (for
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Journal of Combinatorial Mathematics and Combinatorial Computing
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Applications of Fibonacci numbers, Vol. 8 (Rochester, NY, 1998)
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requires three terms in its greedy expansion if and only if
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to be represented, by repeatedly performing the replacement
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requires four terms in its greedy expansion if and only if
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Spiess, O. (1907), "Über eine Klasse unendlicher Reihen",
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requires two terms in its greedy expansion if and only if
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results in the closest possible underestimate of 1 by any
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up to the next larger integer, and the remaining fraction
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up to the next larger integer, and the remaining fraction
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Beyträge zum Gebrauche der Mathematik und deren Anwendung
2424:, respectively. In addition, the greedy expansion of any 3032:(1880), "On a point in the theory of vulgar fractions", 2963:(1983), "Pseudofree actions and the greedy algorithm", 1785:, one of the two solutions of the polynomial equation 1568:
have an expansion with three or fewer terms, but when
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of the remaining fraction is 3 and the denominator is
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while other methods lead to the much better expansion
2632: 2604: 2572: 2543: 2523: 2451: 2287: 1627: 1332: 1004: 757: 608: 365: 256: 228: 192: 160: 3162: 3141: 3114: 2779:, Dordrecht: Kluwer Acad. Publ., pp. 155–163, 1117:
Maximum-length expansions and congruence conditions
154:The expansion produced by this method for a number 2638: 2618: 2578: 2558: 2529: 2509: 2364: 1743: 1579:case being covered by the congruence relationship 1427: 1069: 924: 812: 743: 446: 351: 242: 198: 166: 54:. An Egyptian fraction is a representation of an 1150: 925:Sylvester's sequence and closest approximation 855:has a much shorter non-greedy representation, 3092: 2707: 823:suggests an even more badly-behaved example, 27:Simple method for finding Egyptian fractions. 8: 2741:(1922), "On Kellogg's diophantine problem", 1435:is in simplest terms. The simplest fraction 2183:, the next term in the greedy expansion is 1778:approximation for the roots of a polynomial 1769: 222:Fibonacci's algorithm expands the fraction 3099: 3085: 3077: 2430:expansions of several well known constants 2936: 2631: 2608: 2603: 2571: 2542: 2522: 2478: 2465: 2452: 2450: 2392:On-Line Encyclopedia of Integer Sequences 2346: 2333: 2320: 2307: 2294: 2286: 1776:describe a method of finding an accurate 1725: 1712: 1699: 1686: 1673: 1660: 1647: 1634: 1626: 1587:More generally the sequence of fractions 1421: 1394: 1393: 1387: 1367: 1352: 1348: 1333: 1331: 1057: 1044: 1031: 1018: 1005: 1003: 797: 784: 771: 758: 756: 731: 727: 723: 719: 715: 711: 707: 703: 694: 684: 680: 676: 667: 657: 648: 635: 622: 609: 607: 431: 418: 405: 392: 379: 366: 364: 332: 317: 313: 298: 279: 270: 257: 255: 232: 227: 191: 159: 144: 2799:, Berlin: Zweyter Theil, pp. 99–104 1097:, 1) requires at least five terms. 3154:Greedy algorithm for Egyptian fractions 2703: 2655: 1098: 148: 36:greedy algorithm for Egyptian fractions 2691: 2674: 2662: 1773: 2904:Sigler, Laurence E. (trans.) (2002), 2687: 1106: 820: 7: 3180:Generalizations of Fibonacci numbers 3175:List of things named after Fibonacci 3170:Fibonacci numbers in popular culture 1146: 2726:Nouvelles Annales des Mathématiques 602:For instance, this method expands 25: 3070:, W. H. Freeman, pp. 271–277 2925:Approximating 1 from below using 1765:Approximation of polynomial roots 2948:Archiv der Mathematik und Physik 1247:; the simplest such fraction is 3035:American Journal of Mathematics 1453:with a three-term expansion is 1145:terms in its greedy expansion. 2434:additional entries in the OEIS 1530:with a four-term expansion is 1412: 1400: 1345: 1336: 990:. Truncating this sequence to 310: 301: 1: 2868:American Mathematical Monthly 2829:American Mathematical Monthly 2744:American Mathematical Monthly 1151:Freitag & Phillips (1999) 486:is the result of simplifying 184:Fibonacci–Sylvester expansion 18:Fibonacci–Sylvester expansion 2074:, which can be expanded as 1901:, which can be expanded as 3236: 2923:Soundararajan, K. (2005), 1850:, there must be a root of 1550:states that all fractions 1109:describes applications in 3185:The Fibonacci Association 3002:Mathematische Zeitschrift 1497:, for then the numerator 176:greedy Egyptian expansion 1512:. The simplest fraction 932:2, 3, 7, 43, 1807, ... ( 2906:Fibonacci's Liber Abaci 2559:{\displaystyle xd>y} 2386:Other integer sequences 1548:Erdős–Straus conjecture 566:after subtracting both 2640: 2620: 2580: 2560: 2531: 2511: 2366: 1745: 1429: 1071: 814: 745: 448: 353: 244: 218:Algorithm and examples 200: 168: 3068:Mathematica in Action 2965:Mathematische Annalen 2641: 2621: 2581: 2561: 2532: 2512: 2367: 1746: 1430: 1072: 815: 746: 550:is what is left from 449: 354: 245: 201: 169: 58:as a sum of distinct 42:, first described by 2630: 2602: 2592:odd greedy expansion 2570: 2541: 2521: 2449: 2285: 1829: = 1, and 1625: 1330: 1002: 930:Sylvester's sequence 755: 606: 363: 254: 226: 206:. However, the term 190: 158: 56:irreducible fraction 3191:Fibonacci Quarterly 3131:The Book of Squares 2908:, Springer-Verlag, 2619:{\displaystyle x/y} 243:{\displaystyle x/y} 208:Fibonacci expansion 180:Sylvester expansion 141:J. J. Sylvester 46:, for transforming 3215:Egyptian fractions 3149:Fibonacci sequence 3014:10.1007/BF01246446 2977:10.1007/BF01455950 2929:Egyptian fractions 2708:Soundararajan 2005 2636: 2616: 2576: 2556: 2527: 2507: 2440:Related expansions 2362: 1770:Stratemeyer (1930) 1741: 1573:≡ 1 or 17 (mod 24) 1495:≡ 1 or 17 (mod 24) 1425: 1067: 810: 741: 444: 349: 240: 196: 164: 52:Egyptian fractions 3220:Greedy algorithms 3202: 3201: 2686:See for instance 2639:{\displaystyle y} 2579:{\displaystyle d} 2530:{\displaystyle d} 2502: 2473: 2460: 2426:irrational number 2354: 2341: 2328: 2315: 2302: 1733: 1720: 1707: 1694: 1681: 1668: 1655: 1642: 1423: 1419: 1382: 1375: 1141:requires at most 1065: 1052: 1039: 1026: 1013: 805: 792: 779: 766: 736: 689: 662: 643: 630: 617: 439: 426: 413: 400: 387: 374: 347: 340: 293: 287: 265: 212:Fibonacci numbers 199:{\displaystyle x} 167:{\displaystyle x} 136:Egyptian fraction 16:(Redirected from 3227: 3101: 3094: 3087: 3078: 3071: 3058: 3030:Sylvester, J. J. 3024: 2995: 2955: 2950:, Third Series, 2941: 2940: 2918: 2899: 2860: 2821: 2800: 2787: 2767: 2733: 2710: 2701: 2695: 2684: 2678: 2672: 2666: 2660: 2645: 2643: 2642: 2637: 2625: 2623: 2622: 2617: 2612: 2585: 2583: 2582: 2577: 2565: 2563: 2562: 2557: 2536: 2534: 2533: 2528: 2516: 2514: 2513: 2508: 2503: 2501: 2493: 2479: 2474: 2466: 2461: 2453: 2423: 2413: 2403: 2377: 2371: 2369: 2368: 2363: 2355: 2347: 2342: 2334: 2329: 2321: 2316: 2308: 2303: 2295: 2274: 2265: 2264: 2238: 2236: 2234: 2233: 2230: 2227: 2198: 2196: 2195: 2192: 2189: 2182: 2181: 2179: 2178: 2175: 2172: 2160: 2146: 2144: 2143: 2140: 2137: 2126: 2109: 2100: 2099: 2073: 2071: 2069: 2068: 2065: 2062: 2033: 2031: 2030: 2027: 2024: 2017: 2015: 2014: 2011: 2008: 1994: 1987: 1973: 1971: 1970: 1967: 1964: 1953: 1936: 1927: 1926: 1900: 1876: 1874: 1873: 1870: 1867: 1849: 1842: 1824: 1806: 1756: 1750: 1748: 1747: 1742: 1734: 1726: 1721: 1713: 1708: 1700: 1695: 1687: 1682: 1674: 1669: 1661: 1656: 1648: 1643: 1635: 1606: 1604: 1603: 1598: 1595: 1582: 1578: 1574: 1567: 1565: 1564: 1559: 1556: 1545: 1543: 1542: 1539: 1536: 1529: 1527: 1526: 1521: 1518: 1511: 1507: 1496: 1489: 1487: 1486: 1481: 1478: 1468: 1466: 1465: 1462: 1459: 1452: 1450: 1449: 1444: 1441: 1434: 1432: 1431: 1426: 1424: 1422: 1420: 1415: 1395: 1388: 1383: 1381: 1380: 1376: 1368: 1358: 1357: 1356: 1334: 1325: 1323: 1322: 1319: 1316: 1302: 1290: 1283: 1281: 1280: 1275: 1272: 1262: 1260: 1259: 1256: 1253: 1246: 1239: 1237: 1236: 1231: 1228: 1218: 1216: 1215: 1212: 1209: 1202: 1200: 1199: 1194: 1191: 1172: 1170: 1169: 1164: 1161: 1140: 1138: 1137: 1132: 1129: 1096: 1094: 1093: 1090: 1087: 1076: 1074: 1073: 1068: 1066: 1058: 1053: 1045: 1040: 1032: 1027: 1019: 1014: 1006: 998: = 4) 989: 987: 985: 984: 979: 976: 965: 963: 961: 960: 955: 952: 941: 920: 919: 917: 916: 913: 910: 903: 901: 900: 897: 894: 887: 885: 884: 881: 878: 871: 869: 868: 865: 862: 854: 852: 851: 848: 845: 838: 836: 835: 832: 829: 819: 817: 816: 811: 806: 798: 793: 785: 780: 772: 767: 759: 750: 748: 747: 742: 737: 735: 695: 690: 688: 668: 663: 661: 649: 644: 636: 631: 623: 618: 610: 597: 595: 594: 591: 588: 581: 579: 578: 575: 572: 565: 563: 562: 559: 556: 549: 547: 546: 543: 540: 533: 531: 530: 527: 524: 517: 515: 514: 511: 508: 501: 499: 498: 495: 492: 485: 483: 482: 479: 476: 469: 467: 466: 463: 460: 453: 451: 450: 445: 440: 432: 427: 419: 414: 406: 401: 393: 388: 380: 375: 367: 358: 356: 355: 350: 348: 346: 345: 341: 333: 323: 322: 321: 299: 294: 292: 288: 280: 271: 266: 258: 249: 247: 246: 241: 236: 205: 203: 202: 197: 173: 171: 170: 165: 124:Leonardo of Pisa 111: 110: 108: 107: 104: 101: 94: 92: 91: 88: 85: 78: 76: 75: 72: 69: 48:rational numbers 40:greedy algorithm 21: 3235: 3234: 3230: 3229: 3228: 3226: 3225: 3224: 3205: 3204: 3203: 3198: 3158: 3137: 3110: 3105: 3075: 3062: 3048:10.2307/2369261 3028: 2999: 2959: 2945: 2938:math.CA/0502247 2922: 2916: 2903: 2881:10.2307/2304960 2864: 2842:10.2307/2305906 2825: 2804: 2791: 2771: 2757:10.2307/2299023 2751:(10): 380–387, 2737: 2723: 2719: 2714: 2713: 2702: 2698: 2685: 2681: 2673: 2669: 2661: 2657: 2652: 2628: 2627: 2600: 2599: 2588:Engel expansion 2568: 2567: 2539: 2538: 2519: 2518: 2494: 2480: 2447: 2446: 2442: 2415: 2405: 2395: 2388: 2383: 2373: 2283: 2282: 2272: 2263: 2260: 2259: 2258: 2253: 2246: 2240: 2231: 2228: 2225: 2224: 2222: 2220: 2213: 2207: 2205: 2193: 2190: 2187: 2186: 2184: 2176: 2173: 2170: 2169: 2167: 2162: 2154: 2148: 2141: 2138: 2135: 2134: 2132: 2120: 2114: 2107: 2098: 2095: 2094: 2093: 2088: 2081: 2075: 2066: 2063: 2060: 2059: 2057: 2055: 2048: 2042: 2040: 2028: 2025: 2022: 2021: 2019: 2012: 2009: 2006: 2005: 2003: 2001: 1989: 1981: 1975: 1968: 1965: 1962: 1961: 1959: 1947: 1941: 1934: 1925: 1922: 1921: 1920: 1915: 1908: 1902: 1898: 1891: 1885: 1883: 1871: 1868: 1865: 1864: 1862: 1856: 1844: 1836: 1830: 1818: 1812: 1792: 1786: 1767: 1762: 1752: 1623: 1622: 1599: 1596: 1591: 1590: 1588: 1580: 1576: 1569: 1560: 1557: 1554: 1553: 1551: 1540: 1537: 1534: 1533: 1531: 1522: 1519: 1516: 1515: 1513: 1509: 1498: 1491: 1482: 1479: 1476: 1475: 1473: 1463: 1460: 1457: 1456: 1454: 1445: 1442: 1439: 1438: 1436: 1396: 1392: 1363: 1359: 1335: 1328: 1327: 1320: 1317: 1307: 1306: 1304: 1292: 1285: 1276: 1273: 1270: 1269: 1267: 1257: 1254: 1251: 1250: 1248: 1241: 1232: 1229: 1226: 1225: 1223: 1222:Every fraction 1213: 1210: 1207: 1206: 1204: 1195: 1192: 1189: 1188: 1186: 1185:Every fraction 1165: 1162: 1157: 1156: 1154: 1133: 1130: 1125: 1124: 1122: 1119: 1091: 1088: 1085: 1084: 1082: 1000: 999: 980: 977: 972: 971: 969: 967: 956: 953: 948: 947: 945: 943: 933: 927: 914: 911: 908: 907: 905: 898: 895: 892: 891: 889: 882: 879: 876: 875: 873: 866: 863: 860: 859: 857: 856: 849: 846: 843: 842: 840: 833: 830: 827: 826: 824: 753: 752: 699: 672: 653: 604: 603: 592: 589: 586: 585: 583: 576: 573: 570: 569: 567: 560: 557: 554: 553: 551: 544: 541: 538: 537: 535: 528: 525: 522: 521: 519: 512: 509: 506: 505: 503: 496: 493: 490: 489: 487: 480: 477: 474: 473: 471: 464: 461: 458: 457: 455: 361: 360: 328: 324: 300: 275: 252: 251: 224: 223: 220: 188: 187: 156: 155: 105: 102: 99: 98: 96: 89: 86: 83: 82: 80: 73: 70: 67: 66: 64: 63: 28: 23: 22: 15: 12: 11: 5: 3233: 3231: 3223: 3222: 3217: 3207: 3206: 3200: 3199: 3197: 3196: 3195: 3194: 3182: 3177: 3172: 3166: 3164: 3160: 3159: 3157: 3156: 3151: 3145: 3143: 3139: 3138: 3136: 3135: 3127: 3118: 3116: 3112: 3111: 3106: 3104: 3103: 3096: 3089: 3081: 3074: 3073: 3060: 3042:(4): 332–335, 3026: 2997: 2971:(4): 501–512, 2957: 2943: 2920: 2914: 2901: 2875:(6): 350–356, 2862: 2836:(3): 135–142, 2823: 2802: 2793:Lambert, J. H. 2789: 2773:Freitag, H. T. 2769: 2739:Curtiss, D. R. 2735: 2720: 2718: 2715: 2712: 2711: 2696: 2679: 2677:, chapter II.7 2667: 2654: 2653: 2651: 2648: 2635: 2615: 2611: 2607: 2575: 2566:and such that 2555: 2552: 2549: 2546: 2526: 2506: 2500: 2497: 2492: 2489: 2486: 2483: 2477: 2472: 2469: 2464: 2459: 2456: 2441: 2438: 2387: 2384: 2361: 2358: 2353: 2350: 2345: 2340: 2337: 2332: 2327: 2324: 2319: 2314: 2311: 2306: 2301: 2298: 2293: 2290: 2281: 2277: 2276: 2270: 2261: 2251: 2244: 2218: 2211: 2203: 2152: 2118: 2111: 2105: 2096: 2086: 2079: 2053: 2046: 2038: 1999: 1995:, the root of 1979: 1945: 1938: 1932: 1923: 1913: 1906: 1896: 1889: 1881: 1854: 1834: 1816: 1790: 1766: 1763: 1740: 1737: 1732: 1729: 1724: 1719: 1716: 1711: 1706: 1703: 1698: 1693: 1690: 1685: 1680: 1677: 1672: 1667: 1664: 1659: 1654: 1651: 1646: 1641: 1638: 1633: 1630: 1621: 1585: 1584: 1470: 1418: 1414: 1411: 1408: 1405: 1402: 1399: 1391: 1386: 1379: 1374: 1371: 1366: 1362: 1355: 1351: 1347: 1344: 1341: 1338: 1264: 1220: 1118: 1115: 1103:perfect number 1099:Curtiss (1922) 1064: 1061: 1056: 1051: 1048: 1043: 1038: 1035: 1030: 1025: 1022: 1017: 1012: 1009: 926: 923: 809: 804: 801: 796: 791: 788: 783: 778: 775: 770: 765: 762: 740: 734: 730: 726: 722: 718: 714: 710: 706: 702: 698: 693: 687: 683: 679: 675: 671: 666: 660: 656: 652: 647: 642: 639: 634: 629: 626: 621: 616: 613: 443: 438: 435: 430: 425: 422: 417: 412: 409: 404: 399: 396: 391: 386: 383: 378: 373: 370: 344: 339: 336: 331: 327: 320: 316: 312: 309: 306: 303: 297: 291: 286: 283: 278: 274: 269: 264: 261: 239: 235: 231: 219: 216: 195: 174:is called the 163: 149:Lambert (1770) 60:unit fractions 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 3232: 3221: 3218: 3216: 3213: 3212: 3210: 3193: 3192: 3188: 3187: 3186: 3183: 3181: 3178: 3176: 3173: 3171: 3168: 3167: 3165: 3161: 3155: 3152: 3150: 3147: 3146: 3144: 3140: 3133: 3132: 3128: 3125: 3124: 3120: 3119: 3117: 3113: 3109: 3102: 3097: 3095: 3090: 3088: 3083: 3082: 3079: 3069: 3065: 3061: 3057: 3053: 3049: 3045: 3041: 3037: 3036: 3031: 3027: 3023: 3019: 3015: 3011: 3007: 3003: 2998: 2994: 2990: 2986: 2982: 2978: 2974: 2970: 2966: 2962: 2958: 2953: 2949: 2944: 2939: 2934: 2930: 2926: 2921: 2917: 2915:0-387-95419-8 2911: 2907: 2902: 2898: 2894: 2890: 2886: 2882: 2878: 2874: 2870: 2869: 2863: 2859: 2855: 2851: 2847: 2843: 2839: 2835: 2831: 2830: 2824: 2820: 2816: 2812: 2808: 2803: 2798: 2794: 2790: 2786: 2782: 2778: 2774: 2770: 2766: 2762: 2758: 2754: 2750: 2746: 2745: 2740: 2736: 2731: 2727: 2722: 2721: 2716: 2709: 2705: 2700: 2697: 2693: 2692:Spiess (1907) 2689: 2683: 2680: 2676: 2671: 2668: 2664: 2659: 2656: 2649: 2647: 2633: 2613: 2609: 2605: 2595: 2593: 2589: 2573: 2553: 2550: 2547: 2544: 2524: 2504: 2498: 2495: 2490: 2487: 2484: 2481: 2475: 2470: 2467: 2462: 2457: 2454: 2439: 2437: 2435: 2431: 2427: 2422: 2418: 2412: 2408: 2402: 2398: 2394:as sequences 2393: 2385: 2381: 2376: 2359: 2356: 2351: 2348: 2343: 2338: 2335: 2330: 2325: 2322: 2317: 2312: 2309: 2304: 2299: 2296: 2291: 2288: 2280: 2269: 2257: 2250: 2243: 2217: 2210: 2202: 2165: 2158: 2151: 2131: =  2130: 2124: 2117: 2112: 2104: 2092: 2085: 2078: 2052: 2045: 2037: 2002:lies between 1998: 1992: 1985: 1978: 1958: =  1957: 1951: 1944: 1939: 1931: 1919: 1912: 1905: 1895: 1888: 1880: 1860: 1853: 1847: 1840: 1833: 1828: 1822: 1815: 1810: 1809: 1808: 1804: 1800: 1796: 1789: 1784: 1779: 1775: 1774:Salzer (1947) 1771: 1764: 1760: 1755: 1738: 1735: 1730: 1727: 1722: 1717: 1714: 1709: 1704: 1701: 1696: 1691: 1688: 1683: 1678: 1675: 1670: 1665: 1662: 1657: 1652: 1649: 1644: 1639: 1636: 1631: 1628: 1620: 1618: 1614: 1610: 1602: 1594: 1572: 1563: 1549: 1525: 1506: 1502: 1494: 1485: 1471: 1448: 1416: 1409: 1406: 1403: 1397: 1389: 1384: 1377: 1372: 1369: 1364: 1360: 1353: 1342: 1339: 1314: 1310: 1300: 1296: 1288: 1279: 1265: 1244: 1235: 1221: 1198: 1184: 1183: 1182: 1180: 1176: 1173:with exactly 1168: 1160: 1152: 1148: 1144: 1136: 1128: 1121:Any fraction 1116: 1114: 1112: 1108: 1104: 1100: 1080: 1062: 1059: 1054: 1049: 1046: 1041: 1036: 1033: 1028: 1023: 1020: 1015: 1010: 1007: 997: 993: 983: 975: 959: 951: 940: 936: 931: 922: 822: 807: 802: 799: 794: 789: 786: 781: 776: 773: 768: 763: 760: 738: 732: 728: 724: 720: 716: 712: 708: 704: 700: 696: 691: 685: 681: 677: 673: 669: 664: 658: 654: 650: 645: 640: 637: 632: 627: 624: 619: 614: 611: 599: 502: =  441: 436: 433: 428: 423: 420: 415: 410: 407: 402: 397: 394: 389: 384: 381: 376: 371: 368: 342: 337: 334: 329: 325: 318: 307: 304: 295: 289: 284: 281: 276: 272: 267: 262: 259: 237: 233: 229: 217: 215: 213: 209: 193: 185: 181: 177: 161: 152: 150: 146: 142: 137: 131: 129: 128:unit fraction 125: 121: 120: 115: 114:ancient Egypt 61: 57: 53: 49: 45: 41: 37: 33: 19: 3189: 3153: 3129: 3121: 3067: 3039: 3033: 3005: 3001: 2968: 2964: 2961:Stong, R. E. 2951: 2947: 2928: 2924: 2905: 2872: 2866: 2833: 2827: 2810: 2806: 2796: 2776: 2748: 2742: 2729: 2725: 2704:Curtiss 1922 2699: 2688:Cahen (1891) 2682: 2670: 2658: 2596: 2443: 2389: 2278: 2267: 2255: 2248: 2241: 2215: 2208: 2200: 2163: 2156: 2149: 2128: 2122: 2115: 2102: 2090: 2083: 2076: 2050: 2043: 2035: 1996: 1990: 1983: 1976: 1955: 1949: 1942: 1929: 1917: 1910: 1903: 1893: 1886: 1878: 1858: 1851: 1845: 1838: 1831: 1826: 1820: 1813: 1802: 1798: 1794: 1787: 1783:golden ratio 1768: 1616: 1612: 1608: 1600: 1592: 1586: 1570: 1561: 1523: 1504: 1500: 1492: 1483: 1446: 1312: 1308: 1298: 1294: 1286: 1277: 1242: 1233: 1196: 1178: 1174: 1166: 1158: 1142: 1134: 1126: 1120: 1111:group theory 1107:Stong (1983) 1078: 995: 991: 981: 973: 957: 949: 928: 821:Wagon (1991) 600: 221: 207: 183: 179: 175: 153: 132: 117: 35: 29: 3123:Liber Abaci 3008:: 767–768, 2813:: 141–148, 2675:Sigler 2002 2663:Sigler 2002 1577:17 (mod 24) 1472:A fraction 1291:, for then 1289:≡ 1 (mod 6) 1266:A fraction 1245:≡ 1 (mod 2) 1147:Mays (1987) 966:instead of 119:Liber Abaci 32:mathematics 3209:Categories 2728:, Ser. 3, 2717:References 2626:for which 2372:(sequence 1751:(sequence 1607:that have 62:, such as 3108:Fibonacci 3064:Wagon, S. 3022:120956180 2993:120347233 2954:: 124–134 2732:: 508–514 2488:− 2360:⋯ 2289:φ 1739:… 1615:for each 1581:2 (mod 3) 1510:1 (mod 6) 1340:− 491:−15 mod 7 305:− 44:Fibonacci 3142:Theories 3066:(1991), 2795:(1770), 2161:for all 2159:) > 0 2125:) < 0 1988:for all 1986:) > 0 1952:) < 0 1899:+ 1) = 0 1843:for all 1841:) > 0 1823:) < 0 1378:⌉ 1365:⌈ 1105:, while 343:⌉ 330:⌈ 290:⌉ 277:⌈ 3163:Related 3056:2369261 2985:0721884 2897:0025512 2889:2304960 2858:0020339 2850:2305906 2819:0888838 2785:1737669 2765:2299023 2432:. Some 2421:A050210 2419::  2411:A050206 2409::  2401:A050205 2399::  2378:in the 2375:A117116 2273:− 5 = 0 2254:) = 324 2235:⁠ 2223:⁠ 2197:⁠ 2185:⁠ 2180:⁠ 2168:⁠ 2145:⁠ 2133:⁠ 2108:− 1 = 0 2070:⁠ 2058:⁠ 2032:⁠ 2020:⁠ 2016:⁠ 2004:⁠ 1972:⁠ 1960:⁠ 1935:− 1 = 0 1875:⁠ 1863:⁠ 1805:− 1 = 0 1757:in the 1754:A048860 1605:⁠ 1589:⁠ 1566:⁠ 1552:⁠ 1544:⁠ 1532:⁠ 1528:⁠ 1514:⁠ 1488:⁠ 1474:⁠ 1467:⁠ 1455:⁠ 1451:⁠ 1437:⁠ 1324:⁠ 1305:⁠ 1282:⁠ 1268:⁠ 1261:⁠ 1249:⁠ 1238:⁠ 1224:⁠ 1217:⁠ 1205:⁠ 1201:⁠ 1187:⁠ 1171:⁠ 1155:⁠ 1139:⁠ 1123:⁠ 1095:⁠ 1083:⁠ 986:⁠ 970:⁠ 962:⁠ 946:⁠ 939:A000058 937::  918:⁠ 906:⁠ 902:⁠ 890:⁠ 886:⁠ 874:⁠ 870:⁠ 858:⁠ 853:⁠ 841:⁠ 837:⁠ 825:⁠ 596:⁠ 584:⁠ 580:⁠ 568:⁠ 564:⁠ 552:⁠ 548:⁠ 536:⁠ 532:⁠ 520:⁠ 516:⁠ 504:⁠ 500:⁠ 488:⁠ 484:⁠ 472:⁠ 468:⁠ 456:⁠ 143: ( 109:⁠ 97:⁠ 93:⁠ 81:⁠ 77:⁠ 65:⁠ 3134:(1225) 3126:(1202) 3054:  3020:  2991:  2983:  2912:  2895:  2887:  2856:  2848:  2817:  2783:  2763:  2517:where 2414:, and 2147:, and 2113:Since 1993:> 1 1974:, and 1940:Since 1811:Since 1546:. The 497:15 × 3 34:, the 3115:Books 3052:JSTOR 3018:S2CID 2989:S2CID 2933:arXiv 2885:JSTOR 2846:JSTOR 2761:JSTOR 2650:Notes 2352:37986 2266:+ 720 2237:) = 0 2199:. If 2166:> 2089:) = 4 2072:) = 0 2034:. If 1877:. If 964:⌋ + 1 182:, or 50:into 38:is a 2910:ISBN 2690:and 2551:> 2417:OEIS 2407:OEIS 2397:OEIS 2380:OEIS 2127:for 1954:for 1916:) = 1825:for 1797:) = 1772:and 1759:OEIS 1503:mod 1315:+ 2) 1303:and 1297:mod 1149:and 1092:1806 1086:1805 1063:1806 1060:1805 935:OEIS 915:8708 899:2799 582:and 145:1880 3044:doi 3010:doi 2973:doi 2969:265 2877:doi 2838:doi 2753:doi 2339:145 2101:+ 8 1848:≥ 2 1731:271 1705:253 1692:109 1619:is 1350:mod 1301:= 2 850:311 834:311 803:363 790:121 764:121 733:225 729:846 725:418 721:093 717:642 713:795 709:612 705:527 686:913 682:180 678:960 674:873 659:309 655:763 641:757 615:121 545:120 437:120 315:mod 186:of 122:of 30:In 3211:: 3050:, 3038:, 3016:, 3006:31 3004:, 2987:, 2981:MR 2979:, 2967:, 2952:12 2931:, 2893:MR 2891:, 2883:, 2873:55 2871:, 2854:MR 2852:, 2844:, 2834:54 2832:, 2815:MR 2809:, 2781:MR 2759:, 2749:29 2747:, 2730:10 2706:; 2404:, 2382:). 2221:+ 2056:+ 1928:+ 1801:− 1761:). 1718:97 1679:31 1666:17 1541:17 1181:. 1113:. 1050:43 968:⌈ 944:⌊ 921:. 904:+ 888:+ 883:63 872:+ 867:12 844:31 828:31 777:33 628:25 598:. 561:15 523:15 513:45 481:15 459:15 398:15 372:15 214:. 178:, 151:. 95:+ 79:= 3100:e 3093:t 3086:v 3072:. 3059:. 3046:: 3040:3 3025:. 3012:: 2996:. 2975:: 2956:. 2942:. 2935:: 2927:n 2919:. 2900:. 2879:: 2861:. 2840:: 2822:. 2811:1 2801:. 2788:. 2768:. 2755:: 2734:. 2694:. 2665:. 2634:y 2614:y 2610:/ 2606:x 2574:d 2554:y 2548:d 2545:x 2525:d 2505:, 2499:d 2496:y 2491:y 2485:d 2482:x 2476:+ 2471:d 2468:1 2463:= 2458:y 2455:x 2357:+ 2349:1 2344:+ 2336:1 2331:+ 2326:9 2323:1 2318:+ 2313:2 2310:1 2305:+ 2300:1 2297:1 2292:= 2275:. 2271:3 2268:x 2262:3 2256:x 2252:3 2249:x 2247:( 2245:3 2242:P 2232:9 2229:/ 2226:1 2219:3 2216:x 2214:( 2212:2 2209:P 2204:3 2201:x 2194:9 2191:/ 2188:1 2177:8 2174:/ 2171:1 2164:x 2157:x 2155:( 2153:2 2150:P 2142:9 2139:/ 2136:1 2129:x 2123:x 2121:( 2119:2 2116:P 2110:. 2106:2 2103:x 2097:2 2091:x 2087:2 2084:x 2082:( 2080:2 2077:P 2067:2 2064:/ 2061:1 2054:2 2051:x 2049:( 2047:1 2044:P 2039:2 2036:x 2029:2 2026:/ 2023:1 2013:2 2010:/ 2007:1 2000:1 1997:P 1991:x 1984:x 1982:( 1980:1 1977:P 1969:2 1966:/ 1963:1 1956:x 1950:x 1948:( 1946:1 1943:P 1937:. 1933:1 1930:x 1924:1 1918:x 1914:1 1911:x 1909:( 1907:1 1904:P 1897:1 1894:x 1892:( 1890:0 1887:P 1882:1 1879:x 1872:1 1869:/ 1866:1 1859:x 1857:( 1855:0 1852:P 1846:x 1839:x 1837:( 1835:0 1832:P 1827:x 1821:x 1819:( 1817:0 1814:P 1803:x 1799:x 1795:x 1793:( 1791:0 1788:P 1736:, 1728:9 1723:, 1715:8 1710:, 1702:7 1697:, 1689:6 1684:, 1676:5 1671:, 1663:4 1658:, 1653:7 1650:3 1645:, 1640:3 1637:2 1632:, 1629:1 1617:x 1613:y 1609:x 1601:y 1597:/ 1593:x 1583:. 1571:y 1562:y 1558:/ 1555:4 1538:/ 1535:4 1524:y 1520:/ 1517:4 1505:x 1501:y 1499:− 1493:y 1484:y 1480:/ 1477:4 1469:. 1464:7 1461:/ 1458:3 1447:y 1443:/ 1440:3 1417:3 1413:) 1410:2 1407:+ 1404:y 1401:( 1398:y 1390:2 1385:= 1373:x 1370:y 1361:y 1354:x 1346:) 1343:y 1337:( 1321:3 1318:/ 1313:y 1311:( 1309:y 1299:x 1295:y 1293:− 1287:y 1278:y 1274:/ 1271:3 1263:. 1258:3 1255:/ 1252:2 1243:y 1234:y 1230:/ 1227:2 1219:. 1214:1 1211:/ 1208:1 1197:y 1193:/ 1190:1 1179:y 1175:x 1167:y 1163:/ 1159:x 1143:x 1135:y 1131:/ 1127:x 1089:/ 1079:k 1055:= 1047:1 1042:+ 1037:7 1034:1 1029:+ 1024:3 1021:1 1016:+ 1011:2 1008:1 996:k 992:k 988:⌉ 982:x 978:/ 974:y 958:x 954:/ 950:y 912:/ 909:1 896:/ 893:1 880:/ 877:1 864:/ 861:1 847:/ 831:/ 808:. 800:1 795:+ 787:1 782:+ 774:1 769:= 761:5 739:, 701:1 697:1 692:+ 670:1 665:+ 651:1 646:+ 638:1 633:+ 625:1 620:= 612:5 593:8 590:/ 587:1 577:3 574:/ 571:1 558:/ 555:7 542:/ 539:1 529:2 526:/ 510:/ 507:6 494:/ 478:/ 475:2 465:7 462:/ 442:. 434:1 429:+ 424:8 421:1 416:+ 411:3 408:1 403:= 395:2 390:+ 385:3 382:1 377:= 369:7 338:x 335:y 326:y 319:x 311:) 308:y 302:( 296:+ 285:x 282:y 273:1 268:= 263:y 260:x 238:y 234:/ 230:x 194:x 162:x 106:3 103:/ 100:1 90:2 87:/ 84:1 74:6 71:/ 68:5 20:)

Index

Fibonacci–Sylvester expansion
mathematics
greedy algorithm
Fibonacci
rational numbers
Egyptian fractions
irreducible fraction
unit fractions
ancient Egypt
Liber Abaci
Leonardo of Pisa
unit fraction
Egyptian fraction
J. J. Sylvester
1880
Lambert (1770)
Fibonacci numbers
Wagon (1991)
Sylvester's sequence
OEIS
A000058
Curtiss (1922)
perfect number
Stong (1983)
group theory
Mays (1987)
Freitag & Phillips (1999)
Erdős–Straus conjecture
A048860
OEIS

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