[QUOTE=alpertron;460879]The 315th in the list is: [URL="http://www.mersenne.ca/exponent/611999"]M611999 = 18464214225958267477777390354183 * PRP184199[/URL][/QUOTE]

FWIW

[CODE]time ../../coding/gwnum/lucasPRP M611999-cofactor 1 2 611999 -1
Lucas testing on x^2 - 9*x + 1 ...
Is Lucas PRP!

real 2m21.692s
user 5m2.932s
sys 2m41.120s
[/CODE]

Sometime during Aug 31/Sep 1, a P68 was reported for [URL="http://www.factordb.com/index.php?query=M1471"]M1471[/URL], completing its factorization, making it #316

EDIT:- The cofactor is a proven prime, so mersenne.ca status can be changed from PRP to P

[QUOTE=axn;466979]Sometime during Aug 31/Sep 1, a P68 was reported for [URL="http://www.factordb.com/index.php?query=M1471"]M1471[/URL], completing its factorization, making it #316

EDIT:- The cofactor is a proven prime, so mersenne.ca status can be changed from PRP to P[/QUOTE]

OK, it now shows as a proven prime at mersenne.ca, based on the certificate at factordb.com

The new factor showed up at FactorDB and at mersenne.ca, but not at mersenne.org... presumably mersenne.ca and mersenne.org exchange data both ways daily, so it would get there eventually? But I decided to manually report it to mersenne.org anyway, just to be sure...

"Insufficient information for accurate CPU credit. For stats purposes, assuming factor was found using ECM with B1 = 50000. CPU credit is 0.0000 GHz-days."

If the actual discoverer is a GIMPS user, maybe the database can be adjusted.

[QUOTE=axn;466979]Sometime during Aug 31/Sep 1, a P68 was reported for [URL="http://www.factordb.com/index.php?query=M1471"]M1471[/URL], completing its factorization, making it #316

EDIT:- The cofactor is a proven prime, so mersenne.ca status can be changed from PRP to P[/QUOTE]

It occurred to me to run a screenscraping script to collect all Mersenne exponents under 10,000 known to FactorDB, and crosscheck them with the GIMPS database. I found one more new factor there:

M[M]1489[/M] has a factor: 95909518295775374166321292697000685895150503357477127

(53 digits)

It was [URL="http://factordb.com/index.php?id=1100000000956003192"]reported (by who?) to FactorDB on August 17[/URL]. The remaining 295-digit cofactor is composite, however.

Does anyone know who this person is, who is finding large new factors for very small Mersenne exponents, independently of GIMPS.

Just a month ago, I ran a systematic crosscheck of exponents under 1 million (prompted by [URL="http://mersenneforum.org/showthread.php?t=22501"]this thread[/URL]), and synchronized the data on both FactorDB and GIMPS. Obviously it will be worthwhile to keep checking FactorDB every few weeks, for the very small exponents at least, to see if new ones keep cropping up.

[QUOTE=GP2;467558]Does anyone know who this person is, who is finding large new factors for very small Mersenne exponents, independently of GIMPS.[/QUOTE]
Have you tried contacting SSW?

[QUOTE=xilman;467563]Have you tried contacting SSW?[/QUOTE]

No, but these exponents are a tad larger than the Cunningham project limit.

[QUOTE=GP2;467558]

M[url=https://www.mersenne.org/report_exponent/?exp_lo=1489&full=1]1489[/url] has a factor: 95909518295775374166321292697000685895150503357477127

(53 digits)

It was [URL=http://factordb.com/index.php?id=1100000000956003192]reported (by who?) to FactorDB on August 17[/URL]. The remaining 295-digit cofactor is composite, however.

Does anyone know who this person is, who is finding large new factors for very small Mersenne exponents, independently of GIMPS.
[/QUOTE]

[quote]2017-09-11 kkmrkkblmbrbk F-ECM Factor: 95909518295775374166321292697000685895150503357477127[/quote]

Post #38 on page 4 of the thread [url=http://www.mersenneforum.org/showthread.php?t=21115&page=4]P-1 factoring attempts at smallest-remaining Mersenne numbers with no known factors[/url] might give a clue.

[QUOTE=Dr Sardonicus;467581]Post #38 on page 4 of the thread [url=http://www.mersenneforum.org/showthread.php?t=21115&page=4]P-1 factoring attempts at smallest-remaining Mersenne numbers with no known factors[/url] might give a clue.[/QUOTE]

OK, except these are not exponents with no known factors. In fact, M[M]1471[/M] is now fully factored and M[M]1489[/M] is now 34% factored and the remaining composite cofactor is well within range of NFS. So, if anything, the mystery person might be trying to find "last factors" rather than first factors.

Also, anyone that contributes to these forums would surely manually report any new finds to PrimeNet, which our mystery person is not doing.

[QUOTE=GP2;467589]...and M[M]1489[/M] is now 34% factored and the remaining composite cofactor is well within range of NFS. [/QUOTE]

How do you figure? You said the cofactor is 295 digits, right? So this is either GNFS-295 on the remaining cofactor, or SNFS on the original 1489-bit number.

Both would be world records.

[QUOTE=VBCurtis;467592]How do you figure? You said the cofactor is 295 digits, right? So this is either GNFS-295 on the remaining cofactor, or SNFS on the original 1489-bit number.

Both would be world records.[/QUOTE]

Yes the cofactor is 295 digits, or 977 bits.

I either had a brain freeze or I didn't know what I was talking about. Pick the most charitable explanation.

[QUOTE=VBCurtis;467592]How do you figure? You said the cofactor is 295 digits, right? So this is either GNFS-295 on the remaining cofactor, or SNFS on the original 1489-bit number.

Both would be world records.[/QUOTE]

to be fair other than primes the cofactor can't divisors up to a 106 digit number otherwise the composite divisor would have to divide by one of the primes already given or a prime below the last divisor shown.