Programs for Windows95/98/Me/NT/2000/XP

Factor search for very small Fermat numbers F12 - F24

Richard Crandall, George Woltman and now Fermatsearch, maintain a project to search factors for small Fermat numbers using ECM (Elliptic Curve Method).

The divisor can have up to 60 digits. Prime95, written by George Woltman, and GMP-ECM, are the best programs for ECM.

F24 has 5050446 decimal digits or 16777216 bit. This number is very hard to test, so we use a different method for Fermat numbers greater than F24: modular arithmetics.

Small and average Fermat numbers F24 ~ F2000

Download mmff version 0.27 for Linux 64 bits (CUDA 4.1) (314k update 13 Dec 2012).
Download mmff version 0.28 final for Windows (CUDA 6) (3MB update 10 jul 2014).
Download mmff version 0.28 final source code (196k update 21 Jun 2014).

Download Fermat_44 version 4.4 for Windows (292k update 4 Aug 2003).

Download GMP_Fermat version 2.5 source and binary for Linux 64 bit (74k update 22 Sep 2016)
Download GMP_Fermat version 2.4 binary for Windows 64 bit (133k update 11 december 2011)

mmff is a program written by George Woltman. It has a nice documentation about its use and configuration. The source code may be compiled on Linux and Windows, and requires a Nvidia GPU with compute capability of 2.0 or higher

Fermat.exe is very simple to use and does not require any special instructions.
It uses spare cycles of your computer which would otherwise be wasted. The program causes no interference with other programs that you may be running and may bring you good luck.
Fermat.exe has been tested on many computers and no problems or complaints have been reported using Windows.

You should manually select a range to calculate based on the current status listed on this web. Please send questions and comments via email to the author: Leonid Durman.

GMP-Fermat is a program written by Mark Rodenkirch. It has a short documentation about its use and configuration. The source code may be compiled on DOS, Linux and Windows, as well as PowerPC, Sparc and all the architectures where GMP library can be installed.
The actual version for Linux uses Geoffrey Reynolds' fast assembly routines for mulmod and expmod routines.

MFAC for DOS and Linux has been written by Tony Forbes.
The divisor for F_31 has been found with this program, but today it is approximately 3 to 5 times slower than GMP-Fermat.

Large and very large Fermat numbers ~F2000 ~ F500000

For such superhuge numbers, modular arithmetics is not enough. Square multiplying becomes time-critical. For this task the program should use FFT (Fast Fourier Transform). The actual state of the art is reached using the following programs: FermFact(sieve) + latest PFGW. Recently PFGW was enhanced and now surpasses the pair PRP+Proth. If you use pre-sieved numbers, GeneFer is today the fastest program for the search for a +100,000 or +500,000 digit prime.

Links to the various programs for prime numbers:


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