My new email addresses
 

l.morelli at moreware dot org
l.morelli at fermatsearch dot org

my address at mclink will be soon discardeed.

Luigi

July 21st, 2015
New Fermat factor from FermatSearch!
1132007355 . 2[sup]3578[/sup]+1 is a Factor of F[sub]3576[/sub]!!!
Takahiro Nohara found a new Fermat factor using an i7 Ivy-bridge processor with 4GB of RAM, sieving by Fougeron's FermFact, and found as a prime using PFGW.
Congratulations to Takahiro Nohara from FermatSearch, for his 12th factor, the second of the year!

August 16th, 2015
New Fermat factor from FermatSearch!
787703529 . 2[sup]3854[/sup]+1 is a Factor of F[sub]3850[/sub]!!!
Maximilian Pacher found his 6th Fermat factor using NewPGen, PRP and WinPFGW for his test.
Congratulations to Maxi from FermatSearch, for the third factor of the year!

Again!
 

August 17th, 2015
Another Fermat factor from FermatSearch!
1127899657 . 23732+1 is a Factor of F3730!!!
Takahiro Nohara found his 13th Fermat factor today, the fourth factor of this year.
Congratulations from Fermatserch!

New Fermat factor
 

I am pleased to report a new Fermat number factor:

4,004,779,405 * 2^2288 + 1 is a factor of F2286

I discovered this using my "pmfs" program, which uses the GMP library, running on an HPE Integrity Superdome X server. Search ranges were coordinated through fermatsearch.org.

[QUOTE=Gary;417332]I am pleased to report a new Fermat number factor:

4,004,779,405 * 2^2288 + 1 is a factor of F2286

I discovered this using my "pmfs" program, which uses the GMP library, running on an HPE Integrity Superdome X server. Search ranges were coordinated through fermatsearch.org.[/QUOTE]

Cool. Is the source code available?

Hi,
I found a result on my reports page on mersenne.org that indicated that 36204694129087842739610650509313 is a factor of F12 but this number is a product of other F12 factors (per factordb.com). The only other time I've had this issue is when I haven't filled the worktodo file for "prime95".
The problem is that the machine that generated this result is sitting at an old employer of mine and I've had no access to it for almost 6 months(and it's still going :grin:). So is there a bug in prime95 that could account for this OR has the assignment text been corrupted in-transit OR is someone at the old employer trying to mess with my head.

On mersenne .org, for F12, ECM workers are reporting this factors:
1256132134125569
190276431449381650433
239009526063309834309009409
239012339910309306759513718485221377
36204694129087842739610650509313

1256132134125569 is know as 76668221077 * 2^14+1

I wonder why the others are not know as:
11613551724205423 * 2^14+1
3646995942128140782303 * 2^16+1
3647038878025959880974025245441 *2^16+1
1104879581576167075793782059 * 2^15+1

Could someone enlighten me?
Thank you.

You have to add the following at the end of the ECM2 line that you use to try to factor F12:

[code],"114689",26017793,63766529,190274191361,1256132134125569,568630647535356955169033410940867804839360742060818433"[/code]

In this way, Prime95 does not return known factors of this Fermat number.

[QUOTE=f11ksx;419963]On mersenne .org, for F12, ECM workers are reporting this factors:
1256132134125569
190276431449381650433
239009526063309834309009409
239012339910309306759513718485221377
36204694129087842739610650509313
[/QUOTE]
There are six known prime factors of F12. They are
[CODE]7*2^14+1
397*2^16+1
973*2^16+1
11613415*2^14+1
76668221077*2^14+1
k_50*2^15+1[/CODE]Only one of the factors that you listed is prime, the others are composite products of prime factors:
[CODE]1256132134125569: 1256132134125569
190276431449381650433: 114689 26017793 63766529
239009526063309834309009409: 190274191361 1256132134125569
239012339910309306759513718485221377: 114689 26017793 63766529 1256132134125569
36204694129087842739610650509313: 114689 26017793 63766529 190274191361[/CODE]If you take a couple small factors, e.g. (a*2^14+1) and (b*2^14+1) and multiply, you will get (a*2^14+1) * (b*2^14+1) = (ab*2^14+a+b)*2^14+1, and that is indeed what you obtained.

Follow alpertron's advice to modify the workunit lines in your worktodo.txt

Thank you
:hello: