Distributed Search for Fermat Number Divisors Project News

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Distributed Search for Fermat Number Divisors Project News

Postby Jwb52z » Sun Oct 02, 2005 3:37 am

October 1 2005

Search for factors in small Fermat numbers may be achieved using ECM: Prime95 and GMPE-ECM 6.0.1 have the capability to search for such factors. On Mersenne pages, http://www.mersenne.org/ecmf.htm , you may find a special note for Pentium 4 users: Rather than run ECM on 2^N+1 it is more efficient to run ECM on 2^(2N)-1. As an added bonus, this can find factors for smaller Fermat numbers. For example, say you want to do some ECM on 2^131072+1 with bounds 3,000,000.
Since 2^262144-1 = (2^131072+1)*(2^65536+1)*...*(2^2+1)*(2^1+1), running a curve on 2^262144-1 with bounds 3,000,000 is not only faster, it can find factors for F17, F16, F15, F14, F13, or F12. Before you begin, download lowm.txt, ftp://mersenne.org/gimps/lowm.txt , so that already known factors are not reported.

September 30 2005

Mark Rodenkirch found a major bug this past weekend in GMP-Fermat. If you've used it, he suggests you start over with the new release.

August 30 2005

Curtis Cooper, announced his factorof a Fermat number: 27.2^672007+1 divides F672005!
Congratulations Curtis!
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