Nice find. 133 bits, and prime.
On another note, has anybody spotted the monster (first) factor recently found for M2357?
That was something: over 200 bits and very rough. Completely out of reach for P-1, as per the ludicrous number of ghz-days indicated in James' site.

So the only solution would be an ecm of a gnfs factorisation?

[url]https://www.mersenneforum.org/showthread.php?p=512799#post512799[/url]

P-1 found a factor in stage #1, B1=685000.
UID: Jwb52z/Clay, M90918851 has a factor: 4543028685782507004545407 (P-1, B1=685000)

81.910 bits.

[QUOTE=axn;512850][url]https://www.mersenneforum.org/showthread.php?p=512799#post512799[/url][/QUOTE]

[url]https://www.mersenneforum.org/showpost.php?p=513034&postcount=460[/url]

Thank you petrw1

[QUOTE=petrw1;513135][url]https://www.mersenneforum.org/showpost.php?p=513034&postcount=460[/url][/QUOTE]

Not exactly. M2357 is fully factored, as the remaining cofactor was certified prime, whereas M2557 is not yet at that stage for the cofactor is not a PRP.

But if you were referring to the much praised first factors for <10k exponents, then yes, lightning has striken twice... :beer:!

Wow a 3rd for Ryan
 

[QUOTE=lycorn;513285]But if you were referring to the much praised first factors for <10k exponents, then yes, lightning has striken twice... :beer:![/QUOTE]

2377 Factored 227428848043888440045045261533777705948742974440394358593

Date User Type Result
2019-04-13 Ryan Propper F-ECM Factor: 227428848043888440045045261533777705948742974440394358593

We may say lightning strikes thrice! :party:

I would like to know what program Ryan Propper is using. Although the results are reported as "F-ECM", I´m not so sure about it.

[QUOTE=lycorn;513634]I would like to know what program Ryan Propper is using. Although the results are reported as "F-ECM", I´m not so sure about it.[/QUOTE]

The three factors found so far in the 2k range are all impossibly non-smooth for P−1. The cofactors were surely impossibly large for NFS, they are about 650 digits even after the new factors.

Factors of 56, 57, and 62 digits are perfectly consistent with very deep but entirely feasible ECM, if you throw enough cores at it. Given Ryan's track record of envelope-pushing discoveries, he surely has sufficient resources at his disposal.

[QUOTE=GP2;513653]

Factors of 56, 57, and 62 digits are perfectly consistent with very deep but entirely feasible ECM, if you throw enough cores at it. Given Ryan's track record of envelope-pushing discoveries, he surely has sufficient resources at his disposal.[/QUOTE]

Yes, I agree. But my point has to do with the way the factors were reported.

First off, the Cleared Report has no mention to number of curves nor bounds used. Fair enough, there are other cases where we see that happen. User newalex, for one, who has recently been finding many factors for small exponents. He appears to be using AVX-512 AWS systems, that´s probably the reason.

Second, there are no traces of Ryan´s activity in the Exponent Status report for these exponents, except the finding.

Third, although I have no hard figures for that, I am under the impression that the number of curves recorded for these exponents hasn´t increased much lately. It could have been a case of great luck, of course, but, on [B]three[/B] exponents?

This reminds that when a factor was eventually found for M1061, a couple of years ago, F-ECM showed up in the report, although other method had been used. I think it was SNFS.

The importance of all this lies somewhere between nil and nothing, of course, but I just felt curious about it...:smile: