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Fermat's factorization method

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In its simplest form, Fermat's method might be even slower than trial division (worst case). Nonetheless, the combination of trial division and Fermat's is more effective than either by itself.
1512: 3401: 1724: 1683: 1236: 577: 2909: 2649:, which are the "worst-case". The primary improvement that quadratic sieve makes over Fermat's factorization method is that instead of simply finding a square in the sequence of 1571: 2394: 186: 459: 2532: 2488: 2081: 1821: 1536: 1461: 1317: 1260: 863: 2627: 899: 240: 39: 985: 2942: 2680: 1990: 1945: 770: 738: 513: 2209: 2137: 2048: 2017: 1848: 1178: 935: 702: 676: 276: 2579: 2350: 2319: 1149: 807: 2444: 2421: 990: 288: 1466:
Trial division would normally try up to 48,432; but after only four Fermat steps, we need only divide up to 47830, to find a factor or prove primality.
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produces 3, 4, 7, 8, 12, and 19 modulo 20 for these values. It is apparent that only the 4 from this list can be a square. Thus,
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is a square, and it does this in a highly efficient manner. The end result is the same: a difference of squares mod
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Suppose N has more than two prime factors. That procedure first finds the factorization with the least values of
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b2 is a square, modulo modulus: FermatSieve(N, a, aend, astep * modulus, NextModulus)
3058: 3033: 2962: 2748: 2703: 1541: 3417: 2843: 2585:. R. Lehman devised a systematic way to do this, so that Fermat's plus trial division can factor N in 3412: 3304: 3286: 3261: 3223: 2967: 2728: 2723: 392:
are also odd, so those halves are integers. (A multiple of four is also a difference of squares: let
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In this regard, Fermat's method gives diminishing returns. One would surely stop before this point:
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a square: a ← a + 1 b2 ← a*a - N // equivalently: // b2 ← b2 + 2*a + 1
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has a factor close to its square root, the method works quickly. More precisely, if
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by 10. In this example, N is 17 mod 20, so subtracting 17 mod 20 (or adding 3),
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The fundamental ideas of Fermat's factorization method are the basis of the
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Fermat's method works best when there is a factor near the square-root of
2274:-values remain; that is, when (aend-astart)/astep is small. Also, because 2278:
s step-size is constant, one can compute successive b2's with additions.
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by 1. The second attempt also fails, because 282 is again not a square.
1262:, the method requires only one step; this is independent of the size of 2815: 192: 129: 2234:
One generally chooses a power of a different prime for each modulus.
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the bound for trial division is 47830. A reasonable choice could be
1637:{\displaystyle a_{\mathrm {max} }-{\sqrt {a_{\mathrm {max} }^{2}-N}}} 2806: 2241:-values (start, end, and step) and a modulus, one can proceed thus: 1319:
rounded up to the next integer, which is 48,433, we can tabulate:
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This all suggests a combined factoring method. Choose some bound
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FermatSieve(N, astart, aend, astep, modulus) a ← astart
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In practice, one wouldn't bother with that last row until
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The third try produces the perfect square of 441. Thus,
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indicate that algorithm is for numbers of special forms
2682:, it finds a subset of elements of this sequence whose 2057:
This can be performed with any modulus. Using the same
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It is not necessary to compute all the square-roots of
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values can be tried, and try to factor each resulting
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Each odd number has such a representation. Indeed, if
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steps. This is a bad way to prove primality. But if
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The values repeat with each increase of 809:is the smallest factor ≄ the square-root of 2690:that, if nontrivial, can be used to factor 1274:Consider trying to factor the prime number 2910: 2896: 2888: 1514:; use Fermat's method for factors between 987:, so the number of steps is approximately 468:a ← ceiling(sqrt(N)) b2 ← a*a - N 2859: 2805: 2660: 2654: 2606: 2602: 2590: 2563: 2558: 2495: 2451: 2428: 2405: 2357: 2334: 2329: 2303: 2298: 2293:If the approximate ratio of two factors ( 2195: 2189: 2123: 2117: 2062: 2034: 2028: 2003: 1997: 1970: 1964: 1925: 1919: 1834: 1828: 1802: 1697: 1696: 1690: 1656: 1655: 1649: 1620: 1608: 1607: 1601: 1585: 1584: 1578: 1550: 1549: 1543: 1521: 1519: 1497: 1481: 1480: 1474: 1436: 1302: 1300: 1245: 1243: 1218: 1214: 1196: 1193: 1156: 1130: 1097: 1091: 1074: 1060: 1054: 1043: 1033: 1020: 1009: 992: 969: 946: 913: 874: 835: 818: 788: 745: 713: 683: 657: 551: 538: 532: 523:rounded up to the next integer, which is 494: 445: 426: 420: 361: 339: 325: 303: 290: 254: 200: 169: 156: 144: 106:Learn how and when to remove this message 2882:Fermat's Factorization Online Calculator 2759:Table of Gaussian integer factorizations 2050:which ends in 4 mod 20 and, if square, 1852: 1731: 1719:{\displaystyle a_{\mathrm {max} }=55000} 1678:{\displaystyle a_{\mathrm {max} }=48436} 1321: 585: 2775: 1231:{\displaystyle {\left(4N\right)}^{1/4}} 125:, is based on the representation of an 1947:, nor even examine all the values for 572:{\displaystyle b^{2}=78^{2}-5959=125} 7: 2844:"Speeding Fermat's factoring method" 44:adding citations to reliable sources 2876:Fermat's factorization running time 2019:must be 1 mod 20, which means that 1427:is an integer. But observe that if 2396:, and Fermat's method, applied to 1704: 1701: 1698: 1663: 1660: 1657: 1615: 1612: 1609: 1592: 1589: 1586: 1566:{\displaystyle a_{\mathrm {max} }} 1557: 1554: 1551: 1488: 1485: 1482: 1269: 14: 3119:Special number field sieve (SNFS) 3113:General number field sieve (GNFS) 3458:Integer factorization algorithms 20: 2352:can be picked near that value. 2252:: b2 ← a*a - N 1797:When considering the table for 941:be the largest subroot factor. 55:"Fermat's factorization method" 31:needs additional citations for 2616: 2595: 2515: 2500: 2471: 2456: 2389:{\displaystyle Nuv=cv\cdot du} 1644:. In the above example, with 1167: 1161: 1088: 1071: 1051: 1030: 1006: 994: 966: 954: 852: 840: 229: 217: 214: 202: 181:{\displaystyle N=a^{2}-b^{2}.} 1: 2861:10.1090/S0025-5718-99-01133-3 2156:3 or 5 or 11 or 13 modulo 16 865:is the largest factor ≀ root- 454:{\displaystyle a^{2}-N=b^{2}} 119:Fermat's factorization method 3077:Lenstra elliptic curve (ECM) 2744:Euler's factorization method 2709:Factorization of polynomials 2527:{\displaystyle \gcd(N,du)=d} 2483:{\displaystyle \gcd(N,cv)=c} 2076:{\displaystyle N=2345678917} 1816:{\displaystyle N=2345678917} 411:One tries various values of 2783:Lehman, R. Sherman (1974). 2054:will end in 2 or 8 mod 10. 1531:{\displaystyle {\sqrt {N}}} 1456:{\displaystyle a-b=47830.1} 1431:had a subroot factor above 1312:{\displaystyle {\sqrt {N}}} 1295:throughout. Going up from 1270:Fermat's and trial division 1255:{\displaystyle {\sqrt {N}}} 858:{\displaystyle a-b=N/(a+b)} 3474: 3384:Exponentiation by squaring 3067:Continued fraction (CFRAC) 2848:Mathematics of Computation 2837:, vol. 2, p. 256 2793:Mathematics of Computation 2785:"Factoring Large Integers" 2643:general number field sieve 2622:{\displaystyle O(N^{1/3})} 894:{\displaystyle N=1\cdot N} 235:{\displaystyle (a+b)(a-b)} 3431: 1726:giving a bound of 28937. 980:{\displaystyle a=(c+d)/2} 869:. If the procedure finds 134:difference of two squares 2400:, will find the factors 3297:Greatest common divisor 2675:{\displaystyle a^{2}-n} 1985:{\displaystyle a^{2}-N} 1940:{\displaystyle a^{2}-N} 765:{\displaystyle a+b=101} 489:For example, to factor 3408:Modular exponentiation 2676: 2623: 2575: 2528: 2484: 2440: 2417: 2390: 2346: 2315: 2282:Multiplier improvement 2205: 2133: 2077: 2044: 2013: 1986: 1941: 1844: 1817: 1720: 1679: 1638: 1567: 1532: 1508: 1457: 1313: 1256: 1232: 1174: 1145: 1112: 981: 931: 895: 859: 803: 766: 734: 733:{\displaystyle a-b=59} 698: 672: 573: 519:is the square root of 509: 508:{\displaystyle N=5959} 455: 371: 278:is a factorization of 272: 236: 182: 3135:Shanks's square forms 3059:Integer factorization 3034:Sieve of Eratosthenes 2749:Integer factorization 2704:Completing the square 2677: 2624: 2576: 2529: 2485: 2441: 2418: 2391: 2347: 2316: 2206: 2204:{\displaystyle a^{2}} 2134: 2132:{\displaystyle a^{2}} 2078: 2045: 2043:{\displaystyle b^{2}} 2014: 2012:{\displaystyle a^{2}} 1987: 1942: 1845: 1843:{\displaystyle b^{2}} 1818: 1721: 1680: 1639: 1568: 1533: 1509: 1458: 1314: 1257: 1233: 1175: 1146: 1113: 982: 932: 896: 860: 804: 767: 735: 704:, and the factors of 699: 673: 574: 510: 456: 372: 273: 237: 183: 3413:Montgomery reduction 3287:Function field sieve 3262:Baby-step giant-step 3108:Quadratic sieve (QS) 2764:Unique factorization 2724:Monoid factorisation 2653: 2589: 2557: 2494: 2450: 2427: 2404: 2356: 2328: 2297: 2270:is stopped when few 2237:Given a sequence of 2188: 2116: 2061: 2027: 1996: 1963: 1918: 1827: 1801: 1689: 1648: 1577: 1542: 1518: 1473: 1435: 1299: 1242: 1192: 1173:{\displaystyle O(N)} 1155: 1129: 991: 945: 930:{\displaystyle N=cd} 912: 873: 817: 787: 744: 712: 697:{\displaystyle b=21} 682: 671:{\displaystyle a=80} 656: 531: 515:, the first try for 493: 419: 289: 271:{\displaystyle N=cd} 253: 199: 143: 40:improve this article 3423:Trachtenberg system 3389:Integer square root 3330:Modular square root 3049:Wheel factorization 3001:Quadratic Frobenius 2981:Lucas–Lehmer–Riesel 2884:, at windowspros.ru 2574:{\displaystyle u/v} 2345:{\displaystyle v/u} 2321:) is known, then a 2314:{\displaystyle d/c} 1625: 1281:, but also compute 1144:{\displaystyle c=1} 802:{\displaystyle a+b} 191:That difference is 3315:Extended Euclidean 3254:Discrete logarithm 3183:Schönhage–Strassen 3039:Sieve of Pritchard 2854:(228): 1729–1737. 2672: 2633:Other improvements 2619: 2571: 2524: 2480: 2439:{\displaystyle du} 2436: 2416:{\displaystyle cv} 2413: 2386: 2342: 2311: 2260:a ← a + astep 2201: 2129: 2073: 2040: 2009: 1982: 1937: 1840: 1813: 1716: 1675: 1634: 1603: 1563: 1528: 1504: 1453: 1309: 1252: 1228: 1188:differs less than 1170: 1141: 1125:is prime (so that 1108: 977: 927: 901:, that shows that 891: 855: 799: 762: 730: 694: 668: 569: 505: 485:// or a + sqrt(b2) 466:// N should be odd 451: 367: 268: 232: 178: 3445: 3444: 3044:Sieve of Sundaram 2842:McKee, J (1999). 2835:Oeuvres de Fermat 2754:Program synthesis 2729:Pascal's triangle 2232: 2231: 1912: 1911: 1793:Sieve improvement 1790: 1789: 1632: 1526: 1502: 1421: 1420: 1307: 1250: 1079: 1048: 1038: 1025: 650: 649: 479:// a ← a + 1 464:FermatFactor(N): 355: 319: 116: 115: 108: 90: 3465: 3394:Integer relation 3367:Other algorithms 3272:Pollard kangaroo 3163:Ancient Egyptian 3021:Prime-generating 3006:Solovay–Strassen 2919:Number-theoretic 2912: 2905: 2898: 2889: 2878:, at blogspot.in 2865: 2863: 2838: 2820: 2819: 2809: 2800:(126): 637–646. 2789: 2780: 2681: 2679: 2678: 2673: 2665: 2664: 2628: 2626: 2625: 2620: 2615: 2614: 2610: 2580: 2578: 2577: 2572: 2567: 2533: 2531: 2530: 2525: 2489: 2487: 2486: 2481: 2445: 2443: 2442: 2437: 2422: 2420: 2419: 2414: 2395: 2393: 2392: 2387: 2351: 2349: 2348: 2343: 2338: 2320: 2318: 2317: 2312: 2307: 2228:4 or 5 modulo 9 2224: 2210: 2208: 2207: 2202: 2200: 2199: 2152: 2138: 2136: 2135: 2130: 2128: 2127: 2086: 2085: 2082: 2080: 2079: 2074: 2053: 2049: 2047: 2046: 2041: 2039: 2038: 2022: 2018: 2016: 2015: 2010: 2008: 2007: 1991: 1989: 1988: 1983: 1975: 1974: 1958: 1950: 1946: 1944: 1943: 1938: 1930: 1929: 1853: 1849: 1847: 1846: 1841: 1839: 1838: 1822: 1820: 1819: 1814: 1732: 1725: 1723: 1722: 1717: 1709: 1708: 1707: 1684: 1682: 1681: 1676: 1668: 1667: 1666: 1643: 1641: 1640: 1635: 1633: 1624: 1619: 1618: 1602: 1597: 1596: 1595: 1572: 1570: 1569: 1564: 1562: 1561: 1560: 1537: 1535: 1534: 1529: 1527: 1522: 1513: 1511: 1510: 1505: 1503: 1498: 1493: 1492: 1491: 1462: 1460: 1459: 1454: 1322: 1318: 1316: 1315: 1310: 1308: 1303: 1294: 1280: 1261: 1259: 1258: 1253: 1251: 1246: 1237: 1235: 1234: 1229: 1227: 1226: 1222: 1213: 1212: 1208: 1179: 1177: 1176: 1171: 1150: 1148: 1147: 1142: 1117: 1115: 1114: 1109: 1101: 1096: 1095: 1080: 1075: 1064: 1059: 1058: 1049: 1044: 1039: 1034: 1026: 1021: 1013: 986: 984: 983: 978: 973: 936: 934: 933: 928: 900: 898: 897: 892: 864: 862: 861: 856: 839: 808: 806: 805: 800: 771: 769: 768: 763: 739: 737: 736: 731: 707: 703: 701: 700: 695: 677: 675: 674: 669: 586: 578: 576: 575: 570: 556: 555: 543: 542: 526: 522: 514: 512: 511: 506: 460: 458: 457: 452: 450: 449: 431: 430: 376: 374: 373: 368: 366: 365: 360: 356: 351: 340: 330: 329: 324: 320: 315: 304: 277: 275: 274: 269: 241: 239: 238: 233: 187: 185: 184: 179: 174: 173: 161: 160: 123:Pierre de Fermat 111: 104: 100: 97: 91: 89: 48: 24: 16: 3473: 3472: 3468: 3467: 3466: 3464: 3463: 3462: 3448: 3447: 3446: 3441: 3427: 3362: 3324: 3291: 3248: 3192: 3149: 3053: 3015: 2988:Proth's theorem 2930:Primality tests 2924: 2916: 2872: 2841: 2833:Fermat (1894), 2832: 2829: 2824: 2823: 2807:10.2307/2005940 2787: 2782: 2781: 2777: 2772: 2700: 2656: 2651: 2650: 2639:quadratic sieve 2635: 2598: 2587: 2586: 2555: 2554: 2492: 2491: 2448: 2447: 2425: 2424: 2402: 2401: 2354: 2353: 2326: 2325: 2323:rational number 2295: 2294: 2284: 2264: 2222: 2191: 2186: 2185: 2150: 2119: 2114: 2113: 2059: 2058: 2051: 2030: 2025: 2024: 2020: 1999: 1994: 1993: 1966: 1961: 1960: 1956: 1948: 1921: 1916: 1915: 1830: 1825: 1824: 1799: 1798: 1795: 1692: 1687: 1686: 1651: 1646: 1645: 1580: 1575: 1574: 1545: 1540: 1539: 1516: 1515: 1476: 1471: 1470: 1433: 1432: 1297: 1296: 1286: 1279:= 2,345,678,917 1275: 1272: 1240: 1239: 1201: 1197: 1195: 1190: 1189: 1153: 1152: 1127: 1126: 1087: 1050: 989: 988: 943: 942: 910: 909: 871: 870: 815: 814: 785: 784: 742: 741: 710: 709: 705: 680: 679: 654: 653: 547: 534: 529: 528: 524: 520: 491: 490: 487: 441: 422: 417: 416: 409: 341: 335: 334: 305: 299: 298: 287: 286: 251: 250: 197: 196: 165: 152: 141: 140: 112: 101: 95: 92: 49: 47: 37: 25: 12: 11: 5: 3471: 3469: 3461: 3460: 3450: 3449: 3443: 3442: 3440: 3439: 3432: 3429: 3428: 3426: 3425: 3420: 3415: 3410: 3405: 3391: 3386: 3381: 3376: 3370: 3368: 3364: 3363: 3361: 3360: 3355: 3350: 3348:Tonelli–Shanks 3345: 3340: 3334: 3332: 3326: 3325: 3323: 3322: 3317: 3312: 3307: 3301: 3299: 3293: 3292: 3290: 3289: 3284: 3282:Index calculus 3279: 3277:Pohlig–Hellman 3274: 3269: 3264: 3258: 3256: 3250: 3249: 3247: 3246: 3241: 3236: 3231: 3229:Newton-Raphson 3226: 3221: 3216: 3211: 3205: 3203: 3194: 3193: 3191: 3190: 3185: 3180: 3175: 3170: 3165: 3159: 3157: 3155:Multiplication 3151: 3150: 3148: 3147: 3142: 3140:Trial division 3137: 3132: 3127: 3125:Rational sieve 3122: 3115: 3110: 3105: 3097: 3089: 3084: 3079: 3074: 3069: 3063: 3061: 3055: 3054: 3052: 3051: 3046: 3041: 3036: 3031: 3029:Sieve of Atkin 3025: 3023: 3017: 3016: 3014: 3013: 3008: 3003: 2998: 2991: 2984: 2977: 2970: 2965: 2960: 2955: 2953:Elliptic curve 2950: 2945: 2940: 2934: 2932: 2926: 2925: 2917: 2915: 2914: 2907: 2900: 2892: 2886: 2885: 2879: 2871: 2870:External links 2868: 2867: 2866: 2839: 2828: 2825: 2822: 2821: 2774: 2773: 2771: 2768: 2767: 2766: 2761: 2756: 2751: 2746: 2741: 2736: 2731: 2726: 2721: 2716: 2714:Factor theorem 2711: 2706: 2699: 2696: 2671: 2668: 2663: 2659: 2634: 2631: 2618: 2613: 2609: 2605: 2601: 2597: 2594: 2570: 2566: 2562: 2523: 2520: 2517: 2514: 2511: 2508: 2505: 2502: 2499: 2479: 2476: 2473: 2470: 2467: 2464: 2461: 2458: 2455: 2446:quickly. Then 2435: 2432: 2412: 2409: 2385: 2382: 2379: 2376: 2373: 2370: 2367: 2364: 2361: 2341: 2337: 2333: 2310: 2306: 2302: 2283: 2280: 2243: 2230: 2229: 2226: 2219: 2216: 2215: 2212: 2198: 2194: 2182: 2179: 2178: 2175: 2172: 2169: 2168: 2167:0, 1, 4, or 7 2165: 2162: 2158: 2157: 2154: 2147: 2144: 2143: 2140: 2126: 2122: 2110: 2107: 2106: 2103: 2100: 2097: 2096: 2095:0, 1, 4, or 9 2093: 2090: 2072: 2069: 2066: 2037: 2033: 2006: 2002: 1981: 1978: 1973: 1969: 1936: 1933: 1928: 1924: 1910: 1909: 1906: 1903: 1900: 1897: 1891: 1890: 1887: 1884: 1881: 1878: 1872: 1871: 1868: 1865: 1862: 1859: 1837: 1833: 1812: 1809: 1806: 1794: 1791: 1788: 1787: 1784: 1781: 1771: 1770: 1767: 1764: 1758: 1757: 1756:1,254,561,087 1754: 1751: 1745: 1744: 1741: 1738: 1715: 1712: 1706: 1703: 1700: 1695: 1674: 1671: 1665: 1662: 1659: 1654: 1631: 1628: 1623: 1617: 1614: 1611: 1606: 1600: 1594: 1591: 1588: 1583: 1559: 1556: 1553: 1548: 1525: 1501: 1496: 1490: 1487: 1484: 1479: 1452: 1449: 1446: 1443: 1440: 1419: 1418: 1415: 1412: 1409: 1406: 1396: 1395: 1392: 1389: 1386: 1383: 1377: 1376: 1373: 1370: 1367: 1364: 1358: 1357: 1354: 1351: 1348: 1345: 1339: 1338: 1335: 1332: 1329: 1326: 1306: 1271: 1268: 1249: 1225: 1221: 1217: 1211: 1207: 1204: 1200: 1169: 1166: 1163: 1160: 1140: 1137: 1134: 1107: 1104: 1100: 1094: 1090: 1086: 1083: 1078: 1073: 1070: 1067: 1063: 1057: 1053: 1047: 1042: 1037: 1032: 1029: 1024: 1019: 1016: 1012: 1008: 1005: 1002: 999: 996: 976: 972: 968: 965: 962: 959: 956: 953: 950: 926: 923: 920: 917: 890: 887: 884: 881: 878: 854: 851: 848: 845: 842: 838: 834: 831: 828: 825: 822: 798: 795: 792: 761: 758: 755: 752: 749: 729: 726: 723: 720: 717: 693: 690: 687: 667: 664: 661: 648: 647: 644: 641: 638: 632: 631: 628: 625: 622: 616: 615: 612: 609: 606: 600: 599: 596: 593: 590: 568: 565: 562: 559: 554: 550: 546: 541: 537: 504: 501: 498: 463: 448: 444: 440: 437: 434: 429: 425: 415:, hoping that 408: 405: 378: 377: 364: 359: 354: 350: 347: 344: 338: 333: 328: 323: 318: 314: 311: 308: 302: 297: 294: 267: 264: 261: 258: 231: 228: 225: 222: 219: 216: 213: 210: 207: 204: 195:factorable as 189: 188: 177: 172: 168: 164: 159: 155: 151: 148: 121:, named after 114: 113: 28: 26: 19: 13: 10: 9: 6: 4: 3: 2: 3470: 3459: 3456: 3455: 3453: 3437: 3434: 3433: 3430: 3424: 3421: 3419: 3416: 3414: 3411: 3409: 3406: 3403: 3399: 3395: 3392: 3390: 3387: 3385: 3382: 3380: 3377: 3375: 3372: 3371: 3369: 3365: 3359: 3356: 3354: 3351: 3349: 3346: 3344: 3343:Pocklington's 3341: 3339: 3336: 3335: 3333: 3331: 3327: 3321: 3318: 3316: 3313: 3311: 3308: 3306: 3303: 3302: 3300: 3298: 3294: 3288: 3285: 3283: 3280: 3278: 3275: 3273: 3270: 3268: 3265: 3263: 3260: 3259: 3257: 3255: 3251: 3245: 3242: 3240: 3237: 3235: 3232: 3230: 3227: 3225: 3222: 3220: 3217: 3215: 3212: 3210: 3207: 3206: 3204: 3202: 3199: 3195: 3189: 3186: 3184: 3181: 3179: 3176: 3174: 3171: 3169: 3166: 3164: 3161: 3160: 3158: 3156: 3152: 3146: 3143: 3141: 3138: 3136: 3133: 3131: 3128: 3126: 3123: 3121: 3120: 3116: 3114: 3111: 3109: 3106: 3104: 3102: 3098: 3096: 3094: 3090: 3088: 3087:Pollard's rho 3085: 3083: 3080: 3078: 3075: 3073: 3070: 3068: 3065: 3064: 3062: 3060: 3056: 3050: 3047: 3045: 3042: 3040: 3037: 3035: 3032: 3030: 3027: 3026: 3024: 3022: 3018: 3012: 3009: 3007: 3004: 3002: 2999: 2997: 2996: 2992: 2990: 2989: 2985: 2983: 2982: 2978: 2976: 2975: 2971: 2969: 2966: 2964: 2961: 2959: 2956: 2954: 2951: 2949: 2946: 2944: 2941: 2939: 2936: 2935: 2933: 2931: 2927: 2923: 2920: 2913: 2908: 2906: 2901: 2899: 2894: 2893: 2890: 2883: 2880: 2877: 2874: 2873: 2869: 2862: 2857: 2853: 2849: 2845: 2840: 2836: 2831: 2830: 2826: 2817: 2813: 2808: 2803: 2799: 2795: 2794: 2786: 2779: 2776: 2769: 2765: 2762: 2760: 2757: 2755: 2752: 2750: 2747: 2745: 2742: 2740: 2739:Factorization 2737: 2735: 2732: 2730: 2727: 2725: 2722: 2720: 2717: 2715: 2712: 2710: 2707: 2705: 2702: 2701: 2697: 2695: 2693: 2689: 2685: 2669: 2666: 2661: 2657: 2648: 2644: 2640: 2632: 2630: 2611: 2607: 2603: 2599: 2592: 2584: 2568: 2564: 2560: 2551: 2549: 2545: 2541: 2537: 2521: 2518: 2512: 2509: 2506: 2503: 2477: 2474: 2468: 2465: 2462: 2459: 2433: 2430: 2410: 2407: 2399: 2383: 2380: 2377: 2374: 2371: 2368: 2365: 2362: 2359: 2339: 2335: 2331: 2324: 2308: 2304: 2300: 2291: 2289: 2281: 2279: 2277: 2273: 2269: 2263: 2259: 2255: 2251: 2247: 2242: 2240: 2235: 2227: 2220: 2218: 2217: 2213: 2196: 2192: 2183: 2181: 2180: 2176: 2173: 2171: 2170: 2166: 2163: 2160: 2159: 2155: 2148: 2146: 2145: 2141: 2124: 2120: 2111: 2109: 2108: 2104: 2101: 2099: 2098: 2094: 2091: 2088: 2087: 2084: 2070: 2067: 2064: 2055: 2035: 2031: 2004: 2000: 1979: 1976: 1971: 1967: 1954: 1934: 1931: 1926: 1922: 1907: 1904: 1901: 1898: 1896: 1893: 1892: 1888: 1885: 1882: 1879: 1877: 1874: 1873: 1869: 1866: 1863: 1860: 1858: 1855: 1854: 1851: 1850:are squares: 1835: 1831: 1810: 1807: 1804: 1792: 1785: 1782: 1780: 1776: 1773: 1772: 1768: 1765: 1763: 1760: 1759: 1755: 1753:1,254,441,084 1752: 1750: 1747: 1746: 1742: 1739: 1737: 1734: 1733: 1730: 1727: 1713: 1710: 1693: 1672: 1669: 1652: 1629: 1626: 1621: 1604: 1598: 1581: 1546: 1523: 1499: 1494: 1477: 1467: 1464: 1450: 1447: 1444: 1441: 1438: 1430: 1426: 1416: 1413: 1410: 1407: 1405: 1401: 1398: 1397: 1393: 1390: 1387: 1384: 1382: 1379: 1378: 1374: 1371: 1368: 1365: 1363: 1360: 1359: 1355: 1352: 1349: 1346: 1344: 1341: 1340: 1336: 1333: 1330: 1327: 1324: 1323: 1320: 1304: 1293: 1289: 1284: 1278: 1267: 1265: 1247: 1223: 1219: 1215: 1209: 1205: 1202: 1198: 1187: 1183: 1164: 1158: 1151:), one needs 1138: 1135: 1132: 1124: 1119: 1105: 1102: 1098: 1092: 1084: 1081: 1076: 1068: 1065: 1061: 1055: 1045: 1040: 1035: 1027: 1022: 1017: 1014: 1010: 1003: 1000: 997: 974: 970: 963: 960: 957: 951: 948: 940: 924: 921: 918: 915: 906: 904: 888: 885: 882: 879: 876: 868: 849: 846: 843: 836: 832: 829: 826: 823: 820: 812: 796: 793: 790: 782: 778: 773: 759: 756: 753: 750: 747: 727: 724: 721: 718: 715: 691: 688: 685: 665: 662: 659: 645: 642: 639: 637: 634: 633: 629: 626: 623: 621: 618: 617: 613: 610: 607: 605: 602: 601: 597: 594: 591: 588: 587: 584: 582: 566: 563: 560: 557: 552: 548: 544: 539: 535: 518: 502: 499: 496: 486: 483:a - sqrt(b2) 482: 478: 475: 471: 467: 462: 446: 442: 438: 435: 432: 427: 423: 414: 406: 404: 401: 399: 395: 391: 387: 384:is odd, then 383: 362: 357: 352: 348: 345: 342: 336: 331: 326: 321: 316: 312: 309: 306: 300: 295: 292: 285: 284: 283: 281: 265: 262: 259: 256: 247: 245: 226: 223: 220: 211: 208: 205: 194: 193:algebraically 175: 170: 166: 162: 157: 153: 149: 146: 139: 138: 137: 135: 131: 128: 124: 120: 110: 107: 99: 96:February 2022 88: 85: 81: 78: 74: 71: 67: 64: 60: 57: â€“  56: 52: 51:Find sources: 45: 41: 35: 34: 29:This article 27: 23: 18: 17: 3435: 3129: 3117: 3100: 3092: 3011:Miller–Rabin 2993: 2986: 2979: 2974:Lucas–Lehmer 2972: 2851: 2847: 2834: 2797: 2791: 2778: 2734:Prime factor 2691: 2687: 2683: 2636: 2582: 2552: 2547: 2543: 2539: 2535: 2397: 2292: 2287: 2285: 2275: 2271: 2265: 2261: 2257: 2253: 2249: 2245: 2238: 2236: 2233: 2056: 1913: 1894: 1875: 1856: 1796: 1778: 1774: 1761: 1748: 1735: 1728: 1468: 1465: 1428: 1424: 1422: 1403: 1399: 1380: 1361: 1342: 1291: 1287: 1282: 1276: 1273: 1263: 1185: 1181: 1122: 1120: 938: 907: 902: 866: 810: 780: 776: 774: 651: 635: 619: 603: 580: 516: 488: 484: 480: 477: 473: 470:repeat until 469: 465: 461:, a square. 412: 410: 407:Basic method 402: 397: 393: 389: 385: 381: 379: 279: 248: 243: 190: 118: 117: 102: 93: 83: 76: 69: 62: 50: 38:Please help 33:verification 30: 3267:Pollard rho 3224:Goldschmidt 2958:Pocklington 2948:Baillie–PSW 2211:can only be 2164:Squares are 2139:can only be 2102:N mod 16 is 2092:Squares are 783:. That is, 3379:Cornacchia 3374:Chakravala 2922:algorithms 2827:References 2647:semiprimes 2534:. (Unless 2174:N mod 9 is 2089:modulo 16: 2071:2345678917 1811:2345678917 905:is prime. 400:be even.) 66:newspapers 3353:Berlekamp 3310:Euclidean 3198:Euclidean 3178:Toom–Cook 3173:Karatsuba 2719:FOIL rule 2667:− 2378:⋅ 2268:recursion 2161:modulo 9: 1977:− 1932:− 1786:24,582.2 1769:35,419.8 1627:− 1599:− 1442:− 1417:47,830.1 1082:− 1041:− 1018:− 886:⋅ 824:− 813:, and so 719:− 558:− 433:− 346:− 332:− 224:− 163:− 3452:Category 3320:Lehmer's 3214:Chunking 3201:division 3130:Fermat's 2698:See also 2546:divides 2538:divides 2266:But the 2248:modulus 1889:367,179 1783:24,582.9 1766:35,418.1 1414:47,915.1 1411:48,017.5 1408:48,156.3 1375:367,179 3436:Italics 3358:Kunerth 3338:Cipolla 3219:Fourier 3188:FĂŒrer's 3082:Euler's 3072:Dixon's 2995:PĂ©pin's 2816:2005940 2684:product 2225:must be 2153:must be 1886:270,308 1883:173,439 1870:48,436 1743:60,002 1451:47830.1 1372:270,308 1369:173,439 1356:48,436 527:. Then 282:, then 132:as the 130:integer 80:scholar 3418:Schoof 3305:Binary 3209:Binary 3145:Shor's 2963:Fermat 2814:  2629:time. 1953:modulo 1908:605.9 1880:76,572 1867:48,435 1864:48,434 1861:48,433 1740:60,001 1394:605.9 1366:76,572 1353:48,435 1350:48,434 1347:48,433 937:, let 481:return 380:Since 82:  75:  68:  61:  53:  3239:Short 2968:Lucas 2812:JSTOR 2788:(PDF) 2770:Notes 2262:enddo 2258:endif 2250:times 1905:519.9 1902:416.5 1899:276.7 1714:55000 1673:48436 1391:519.9 1388:416.5 1385:276.7 1238:from 643:16.79 640:11.18 589:Try: 87:JSTOR 73:books 3234:Long 3168:Long 2641:and 2490:and 2423:and 2221:and 2149:and 1538:and 1495:> 1337:4th 1325:Try 1285:and 908:For 779:and 740:and 708:are 706:5959 630:441 561:5959 521:5959 503:5959 396:and 388:and 59:news 3398:LLL 3244:SRT 3103:+ 1 3095:− 1 2943:APR 2938:AKS 2856:doi 2802:doi 2583:Nuv 2550:.) 2542:or 2498:gcd 2454:gcd 2398:Nuv 2184:so 2112:so 1334:3rd 1331:2nd 1328:1st 1121:If 760:101 646:21 627:282 624:125 614:80 567:125 472:b2 127:odd 42:by 3454:: 3402:KZ 3400:; 2852:68 2850:. 2846:. 2810:. 2798:28 2796:. 2790:. 2694:. 2290:. 2276:a' 2254:if 2246:do 2214:7 2177:7 2142:9 2105:5 2083:, 1777:− 1402:− 1290:− 1266:. 1118:. 772:. 728:59 692:21 678:, 666:80 611:79 608:78 598:3 549:78 525:78 474:is 246:. 136:: 3404:) 3396:( 3101:p 3093:p 2911:e 2904:t 2897:v 2864:. 2858:: 2818:. 2804:: 2692:n 2688:n 2670:n 2662:2 2658:a 2617:) 2612:3 2608:/ 2604:1 2600:N 2596:( 2593:O 2569:v 2565:/ 2561:u 2548:v 2544:d 2540:u 2536:c 2522:d 2519:= 2516:) 2513:u 2510:d 2507:, 2504:N 2501:( 2478:c 2475:= 2472:) 2469:v 2466:c 2463:, 2460:N 2457:( 2434:u 2431:d 2411:v 2408:c 2384:u 2381:d 2375:v 2372:c 2369:= 2366:v 2363:u 2360:N 2340:u 2336:/ 2332:v 2309:c 2305:/ 2301:d 2288:N 2272:a 2239:a 2223:a 2197:2 2193:a 2151:a 2125:2 2121:a 2068:= 2065:N 2052:b 2036:2 2032:b 2021:a 2005:2 2001:a 1980:N 1972:2 1968:a 1957:a 1949:a 1935:N 1927:2 1923:a 1895:b 1876:b 1857:a 1836:2 1832:b 1808:= 1805:N 1779:b 1775:a 1762:b 1749:b 1736:a 1711:= 1705:x 1702:a 1699:m 1694:a 1670:= 1664:x 1661:a 1658:m 1653:a 1630:N 1622:2 1616:x 1613:a 1610:m 1605:a 1593:x 1590:a 1587:m 1582:a 1558:x 1555:a 1552:m 1547:a 1524:N 1500:N 1489:x 1486:a 1483:m 1478:a 1448:= 1445:b 1439:a 1429:N 1425:b 1404:b 1400:a 1381:b 1362:b 1343:a 1305:N 1292:b 1288:a 1283:b 1277:N 1264:N 1248:N 1224:4 1220:/ 1216:1 1210:) 1206:N 1203:4 1199:( 1186:c 1182:N 1168:) 1165:N 1162:( 1159:O 1139:1 1136:= 1133:c 1123:N 1106:c 1103:2 1099:/ 1093:2 1089:) 1085:c 1077:N 1072:( 1069:= 1066:2 1062:/ 1056:2 1052:) 1046:c 1036:d 1031:( 1028:= 1023:N 1015:2 1011:/ 1007:) 1004:d 1001:+ 998:c 995:( 975:2 971:/ 967:) 964:d 961:+ 958:c 955:( 952:= 949:a 939:c 925:d 922:c 919:= 916:N 903:N 889:N 883:1 880:= 877:N 867:N 853:) 850:b 847:+ 844:a 841:( 837:/ 833:N 830:= 827:b 821:a 811:N 797:b 794:+ 791:a 781:b 777:a 757:= 754:b 751:+ 748:a 725:= 722:b 716:a 689:= 686:b 663:= 660:a 636:b 620:b 604:a 595:2 592:1 581:a 564:= 553:2 545:= 540:2 536:b 517:a 500:= 497:N 447:2 443:b 439:= 436:N 428:2 424:a 413:a 398:d 394:c 390:d 386:c 382:N 363:2 358:) 353:2 349:d 343:c 337:( 327:2 322:) 317:2 313:d 310:+ 307:c 301:( 296:= 293:N 280:N 266:d 263:c 260:= 257:N 244:N 230:) 227:b 221:a 218:( 215:) 212:b 209:+ 206:a 203:( 176:. 171:2 167:b 158:2 154:a 150:= 147:N 109:) 103:( 98:) 94:( 84:· 77:· 70:· 63:· 36:.

Index


verification
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"Fermat's factorization method"
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Pierre de Fermat
odd
integer
difference of two squares
algebraically
modulo
recursion
rational number
quadratic sieve
general number field sieve
semiprimes
Completing the square
Factorization of polynomials
Factor theorem
FOIL rule
Monoid factorisation
Pascal's triangle
Prime factor
Factorization

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