Fermat Search - Leonid Durman's Fermat number factoring site and program. Factoris - Online calculator that factorizes large numbers, specified by formula. The Factor Zone - Aimed at grade school students and teachers, includes course guidelines, worksheets, and factor tables up to 600. Factorization Using the Elliptic Curve Method - 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. FactorWorld - Dedicated to algorithms and computational results on integer factorization. Includes links to papers, downloadable software, and online resources. Factorization of RSA-155 - Announcement of factorization of a 512-bit RSA key using the General Number Field Sieve (GNFS). The XYYXF Project - A collaborative project to produce the factorizations of x^y + y^x for 1<y<x<101. Factoring Papers - Links to papers on the theory and practice of factoring. Factorizations of Near-repdigit Numbers - Factorizations of numbers composed of all the same digit except first and/or last. Integer Factorization - Paul Leyland's list of his own and other factorisations. Factoring Fermat Numbers - Cash prizes for new factors of Fermat numbers Fn, for n = 12 through 22. Discovery of a Lost Factoring Machine - Built by a French amateur, E.-O. Carissan, around 1919. Shallit, Williams and Morain include photographs and references to their paper.