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Old 2009-07-18, 15:12   #23
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Quote:
Originally Posted by ET_ View Post
PFGW with GWNUM 25.11 is already in use to test Fermat factors

Apart from that, I guess that finding factors with ECM is a bit slow-pacing, due to the big numbers involved and the popularity of the task.

Sure enough, there will be a boost in ECM-F after this discovery!

Luigi
A top-producers page for ECM-F could be a motivation for some to do more ECM on Fermatnumbers.
And yes, ECM-F is slow (not to say boring), 7 curves with B1=250k at F23 needed 17 days with one core E6600@2400GHz.
And as prime95 is able to work on Mersennenumbers with composite exponents, I recommen to add 2 more 'result types' (namely F-ECM-F and NF-ECM-F) to the result page of an account.

Matthias
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Old 2009-07-18, 15:22   #24
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Quote:
Originally Posted by MatWur-S530113 View Post
...
I recommen to add 2 more 'result types' (namely F-ECM-F and NF-ECM-F) to the result page of an account.

Matthias
But this is a little deviated from the original purpose of GIMPS to find mersenne prime.
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Old 2009-07-18, 15:32   #25
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Quote:
Originally Posted by MatWur-S530113 View Post
A top-producers page for ECM-F could be a motivation
http://www.mersenne.org/report_top_5...&B1=Get+Report
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Old 2009-07-18, 15:36   #26
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Quote:
Originally Posted by Prime95 View Post
aaaaah, the 'customize'-button (smiley means: I need a pair of glasses)

Thank you!

Matthias
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Old 2009-07-18, 15:57   #27
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Quote:
Originally Posted by wreck View Post
But this is a little deviated from the original purpose of GIMPS to find mersenne prime.
Yes, of course. I think there are already some threads about this topic.
But because prime95/mprime (the proggy used by the project GIMPS) offers a kind of work named 'ECM on Fermat numbers I think that my proposal makes sense for those, who are more interested in factoring M- and F-numbers (and other). And I think there are some user of this kind (like me )

Matthias
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Old 2009-07-18, 20:11   #28
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Quote:
Originally Posted by mdettweiler View Post
Per factordb.com, a 15,770-digit composite cofactor remains.
You mean a 157,770-digit cofactor...

Someone should probably report the new factor to http://www.prothsearch.net/fermat.html
(unless they have and the page just haven't been updated yet).

Last fiddled with by Random Poster on 2009-07-18 at 20:16
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Old 2009-07-18, 20:14   #29
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According to the database, Markus (Syd) ran 5000 curves at B1=35e7. And that was on June 26. I suspect this is just complete nonsense added by the person claiming to be "Bill Gates".
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Old 2009-07-19, 03:37   #30
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Congratulations to everyone involved! This is quite a discovery, the tenth Fermat factor discovered by ECM, the first Fermat factor discovered by ECM since April 1999, and the largest Fermat number so far for which a factor has been found by ECM. As someone who has run many curves in the past, I can assure you that this discovery seemed overdue. A couple years ago, I estimated that the ECM effort since 1999 might have been expected to find an additional 4 factors, but the searched space just had not yielded a single one.

I notice that this factor seems to have shown up a bit late, in that the curves for the 35-digit level had already been completed, with 2000 or so of the 4700 curves needed for the 40-digit level also completed.

What were the B2 bounds and the sigma of the discovery curve, George?

Let's go find another one!
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Old 2009-07-19, 08:31   #31
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Quote:
Originally Posted by Random Poster View Post
You mean a 157,770-digit cofactor...

Someone should probably report the new factor to http://www.prothsearch.net/fermat.html
(unless they have and the page just haven't been updated yet).
I reported it to Wilfrid Keller right now.

Luigi
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Old 2009-07-19, 23:04   #32
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Default Guess what I did this weekend.

I'm a physics major turned computer geek so a great deal of this thread is going over my head. Can anyone direct me to a good "Fermat Factoring 101" site so I can get a better grasp of this process.

David Bessell (no relation to Uncle Fredrick)
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Old 2009-07-20, 03:09   #33
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David Bessel from St Michael's Collegiate School in Australia is our Fermat factor discoverer - a.k.a. Buckle. Here is the results.txt output:

ECM found a factor in curve #3, stage #2
Sigma=7121198363696307, B1=3000000, B2=300000000.
UID: Buckle/G810, F19 has a factor: 37590055514133754286524446080499713
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