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Old 2010-03-28, 02:07   #12
P90 years forever!
Prime95's Avatar
Aug 2002
Yeehaw, FL

753210 Posts

So this is a GMP-ECM success, not a GIMPS success. Congrats also to akruppa who put a lot of work into a specialized stage 2 for Fermat numbers.

Please email me your curve counts when you are done so that the ECM tables can be updated.
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Old 2010-03-28, 02:08   #13
Bemusing Prompter
ixfd64's Avatar
Dec 2002

2·32·7·19 Posts

From another thread:

Originally Posted by Andi47 View Post

This year seems to be a very good one for Fermat factors!!
Too true.
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Old 2010-03-28, 07:20   #14
ckdo's Avatar
Dec 2007
Cleves, Germany

2×5×53 Posts

It's about time for a Fermat subforum...
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Old 2010-03-28, 08:22   #15
philmoore's Avatar
Sep 2002
Tracktown, U.S.A.

3·373 Posts

Congratulations, Mike, and congratulations, Alex! I am truly astounded - no ECM factors of Fermat numbers for over a decade, and then, four within nine months, with the last three within two months! I notice a trend of these showing up a bit on the "late" side, i.e., after the recommended number of curves at the given digit level have already been run, except for the factor of F14. Probably just a coincidence, but it certainly shows that persistence pays off.
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Old 2010-03-28, 12:31   #16
ValerieVonck's Avatar
Mar 2004

34916 Posts

Do you guys take into account the factors found @ ?

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Old 2010-03-28, 13:26   #17
Raman's Avatar
"Mr. Tuch"
Dec 2007
Chennai, India

3×419 Posts

In this website page:

12 1187 2010 Different anonymous provers
Shouldn't the number of digits be 1133?
It is updated correctly with
F12 = 114689 · 26017793 · 63766529 · 190274191361 · 1256132134125569 · 568630647535356955169033410940867804839360742060818433 · C1133

Then, why within that
Composite cofactors of Fermat numbers Fm
F14 is left over?
Because of the fact that it is too trivial to prove that by using the Fermat's Little Theorem?
Similarly, much easier is the case for F12?

Either F12 should be left over within that section
or that number of digits should be correctly updated up to be 1133, right then?
Thus, it should not be incorrectly written up as 1187 digits at all, even especially with the year of proving that the cofactor of F12 is composite as 2010, at all. thus

Last fiddled with by Raman on 2010-03-28 at 13:28
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Old 2010-03-28, 13:47   #18
rajula's Avatar
"Tapio Rajala"
Feb 2010

1001110112 Posts

Congratulations to Michael on this amazing find!

I have recently spent a large portion of my computer resources on F12 as well (over 1800 curves with B1=260M) and reading about this new factor truly made me happy!

The recent boom in finding factors of "small" Fermat numbers is almost mind boggling.
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Old 2010-03-28, 22:05   #19
Buckle's Avatar
Jul 2009
Hobart, Australia

11 Posts
Default A curious entry in results file prime95

does this relate to a factor of F21 or F12 or has my computer had some bizzare error.

[Mon Mar 29 04:35:02 2010]
UID: Buckle/NetworkMan, F21 completed 3 ECM curves, B1=3000000, B2=300000000, Wd4: 244338EA, AID: 3DF716298AB5D181BA2E552234F828AC
ECM found a factor in curve #1, stage #1
Sigma=2333235840349316, B1=3000000, B2=300000000.
UID: Buckle/NetworkMan, F12 has a factor: 396532184444319600058061052745788134326273, AID: 3DF716298AB5D181BA2E552234F828AC
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Old 2010-03-28, 22:20   #20
axn's Avatar
Jun 2003

23·5·127 Posts

396532184444319600058061052745788134326273 = 26017793 × 63766529 × 190274191361 × 1256132134125569

These are all known factors.

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Old 2010-03-29, 05:16   #21
philmoore's Avatar
Sep 2002
Tracktown, U.S.A.

111910 Posts

A correction to my previous post: The recent factor of F22 was not "late", but right on time. The factors of F12 and F19 seem to have shown up a bit late.
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Old 2010-04-11, 12:42   #22
literka's Avatar
Mar 2010

26×3 Posts

Nice result. Congratulations.
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