 The Factor Zone - http://factorzone.tripod.com/ Aimed at grade school students and teachers, includes course guidelines, worksheets, and factor tables up to 600. |
 Factorizations of Near-repdigit Numbers - http://homepage2.nifty.com/m_kamada/math/factorizations.htm Factorizations of numbers composed of all the same digit except first and/or last. |
 Integer Factorization - http://www.leyland.vispa.com/numth/factorization/main.htm Paul Leyland's list of his own and other factorisations. |
 Known Amicable Pairs - http://amicable.homepage.dk/knwnc2.htm A listing of all the known pairs of numbers, each of which is the sum of the aliquot divisors of the other. Complete for smaller numbers, and extending beyond 200 digits. |
 I Love Binary, Primes, and Factors - http://home.earthlink.net/~usondermann/binary.html Divisibility, primes and binary numbers. |
 Factoris - http://wims.unice.fr/~wims/wims.cgi?lang=en&module=tool/algebra/factor.en&cmd=new& Online calculator that factorizes large numbers, specified by formula. |
 RSA Laboratories Factoring Challenge - http://www.rsasecurity.com/rsalabs/node.asp?id=2092 Numbers representative of those used in the RSA cryptosystem are offered for factor attempts with prizes. A Partition List challenge is also provided in order to encourage work on factoring in general. |
 Fermat Search - http://www.fermatsearch.org/ Leonid Durman's Fermat number factoring site and program. |
 Factoring Papers - http://www.crypto-world.com/FactorPapers.html Links to papers on the theory and practice of factoring. |
 Factorization of RSA-155 - http://www.crypto-world.com/announcements/RSA155.txt Announcement of factorization of a 512-bit RSA key using the General Number Field Sieve (GNFS). |
 FactorWorld - http://www.crypto-world.com/FactorWorld.html Dedicated to algorithms and computational results on integer factorization. Includes links to papers, downloadable software, and online resources. |
 Discovery of a Lost Factoring Machine - http://www.cs.uwaterloo.ca/~shallit/Papers/carissan.html Built by a French amateur, E.-O. Carissan, around 1919. Shallit, Williams and Morain include photographs and references to their paper. |
 Sierpinski Problem - http://www.prothsearch.net/sierp.html Sierpinski proved there exist infinitely many odd integers k such that k*2^n+1 is composite for every n. Ray Ballinger coordinates a search to prove or disprove whether k=78557 is the smallest solution. |
 Factoring Fermat Numbers - http://www.perfsci.com/freegoods.htm#fermat Cash prizes for new factors of Fermat numbers Fn, for n = 12 through 22. |
 The XYYXF Project - http://xyyxf.at.tut.by/ A collaborative project to produce the factorizations of x^y + y^x for 1 |
 Factorization Using the Elliptic Curve Method - http://www.alpertron.com.ar/ECM.HTM Java applet that can be used to find 20- or 30-digit factors of numbers or numerical expressions up to 1000 digits long. It also computes the number and sum of divisors, the Euler's totient and moebius functions, and the decomposition of the number in a sum of up to four squares. |