Merry Christmas with FermatSearch!
 

21346190509623 . 2[sup]290[/sup]+1 is a Factor of F[sub]287[/sub]!!!
Roman Maznichenko discovered the sixth factor of the year (and its own sixth factor) just after a month since the last one discovered!
HW: GTX580 (factoring) + 1 core Intel (Haswell) i5-4670K@4000GHz (sieve).
SW: his own program Feromant_CUDA (compiled under Win64 with CUDA 7.0).
He verified it using Feromant (for CPU).

February 21st, 2016
New Fermat factor from FermatSearch!
118807331 . 2[sup]7139[/sup]+1 is a Factor of F[sub]7137[/sub]!!!
Gary Gostin found this new Fermat factor using his GMP-based pmfs program running on an HPE Superdome X system
with 240 Ivy Bridge cores (E7-8890 v2 @ 2.80 GHz).
Congratulations to Gary from FermatSearch, for the first factor of the year!

[QUOTE=ET_;427094]February 21st, 2016
New Fermat factor from FermatSearch!
118807331 . 2[sup]7139[/sup]+1 is a Factor of F[sub]7137[/sub]!!!
Gary Gostin found this new Fermat factor using his GMP-based pmfs program running on an HPE Superdome X system
with 240 Ivy Bridge cores (E7-8890 v2 @ 2.80 GHz).
Congratulations to Gary from FermatSearch, for the first factor of the year![/QUOTE]

Holy crap, that's an impressive system. I wish I had access to that kind of computing power.

[QUOTE=ET_;427094]Congratulations to Gary from FermatSearch, for the first factor of the year![/QUOTE]
Yep! +1! Nice find!

I am pleased to report another new Fermat factor:

60,567,741 * 2^9555 + 1 divides F9552

This was discovered using the same system as described by Luigi below.

Rogue, I just noticed your question below about my source code. Yes, I can make it available. There is not much rocket science in it. It has a pretty vanilla sieve combined with a square-mod loop that calls the GMP library functions. There is currently a lot of cruft in the source from early experiments. Let me clean it up then see if Luigi would post it to FermatSearch.

Does anyone know if the Fermat number site [URL]http://www.prothsearch.net/fermat.html[/URL] is still being maintained? It looks like the last update was over a year ago.

Wilfrid Keller seems to have gone MIA. Several members here have tried to contact him without success. I hope he is all right.

May 25th, 2016
New Fermat factor from FermatSearch!
24142479 . 2[sup]14590[/sup]+1 is a Factor of F[sub]14587[/sub]!!!
Adolf Nordin found this new Fermat factor usingFermFact and PFGW running on his home system
Congratulations to Adolf from FermatSearch, for the third factor of the year!

Now that the prothsearch.net Fermat numbers page is no longer being updated, does anybody know of another site that has comprehensive tables of all known Fermat factors? Apparently fermatsearch.org just points to prothsearch.net.

[QUOTE=jyb;435508]Now that the prothsearch.net Fermat numbers page is no longer being updated, does anybody know of another site that has comprehensive tables of all known Fermat factors? Apparently fermatsearch.org just points to prothsearch.net.[/QUOTE]

I updated the Wilfrid's page and put it [URL="http://www.maths.dur.ac.uk/users/dzmitry.badziahin/Fermat%20factoring%20status.html"]here[/URL].

I more or less check all the data here except "Count of factors according to difference n − m" and the last "Search limits" sections there.

In any case I can not guarantee that the page will be by this address for a reasonably long time. So it can only be used as a temporary location.

[QUOTE=Drdmitry;435707]I updated the Wilfrid's page and put it [URL="http://www.maths.dur.ac.uk/users/dzmitry.badziahin/Fermat%20factoring%20status.html"]here[/URL].

I more or less check all the data here except "Count of factors according to difference n − m" and the last "Search limits" sections there.

In any case I can not guarantee that the page will be by this address for a reasonably long time. So it can only be used as a temporary location.[/QUOTE]

IMO, the "search limits" should point to Luigi's page.

[QUOTE=jyb;435508]Now that the prothsearch.net Fermat numbers page is no longer being updated, does anybody know of another site that has comprehensive tables of all known Fermat factors? Apparently fermatsearch.org just points to prothsearch.net.[/QUOTE]

Use [url]http://prothsearch.net/fermat.html[/url] and supplement it with the eight additional factors (after February 13 2015) listed at [url]http://www.fermatsearch.org/news.html[/url]

I created a CSV file from this combined data, but am wondering how to verify the largest factors. How to use modular exponentiation when 2^2^m becomes enormous? I am probably missing some obvious mathematical point...