[QUOTE=jrk;182148]
[code]Using B1=43000000, B2=388112953420, polynomial Dickson(30), sigma=492002632
Step 1 took 169903ms
Step 2 took 85269ms
********** Factor found in step 2: 270389991140767419113595201012871830378223721738111
Found probable prime factor of 51 digits: 270389991140767419113595201012871830378223721738111
Probable prime cofactor 13097232778890996127721661850226147250346721968629381919532862503065919780081186230385499514937725380715199 has 107 digits
[/code][/QUOTE]

I computed the group order of the factorization:
[code][2 4]

[3 1]

[19 1]

[2473 1]

[17317 1]

[339331 1]

[608297 1]

[859459 1]

[1621679 1]

[4828303 1]

[4983967657 1]
[/code]

So the factor could have been found with as little B1=5e6, B2=5e9.

[quote=jrk;182156]I computed the group order of the factorization:
...[/quote]
How is this computed from the sigma? (or otherwise computed)
Here are some links related to this:
[URL]http://factordb.com/search.php?id=61049323[/URL] (the c157)
[URL]http://factordb.com/search.php?id=66234919[/URL] (the p51)
[URL]http://factordb.com/search.php?id=66581132[/URL] (the c51 you denoted by the factorization given)
[URL]http://factordb.com/search.php?id=66584546[/URL] (a p25 produced by c51-p51)
[quote=jrk;182156]So the factor could have been found with as little B1=5e6, B2=5e9.[/quote]
How much ECM was run at lengths closer to this? That would've been quite something to have found a p51 factor with B1 as low as 5e6! (which is between the B1 values for 40 and 45 digits)
[URL="http://factordb.com/search.php?id=66584546"] [/URL]

[QUOTE=Mini-Geek;182162]How is this computed from the sigma? (or otherwise computed)[/QUOTE]
See: [url=http://www.mersenneforum.org/showthread.php?p=84923]this thread[/url].

But isn't every elliptic curve is different so a different sigma would be a different factorization because each elliptic curve is a different size group? Thats the way I understood it.

The real point is there was a fifty digit number so you needed that size (which we chose) to find it (and we did). At 5e6 very few curves would find it.

[QUOTE=Greebley;182167]But isn't every elliptic curve is different so a different sigma would be a different factorization because each elliptic curve is a different size group? Thats the way I understood it.

The real point is there was a fifty digit number so you needed that size (which we chose) to find it (and we did). At 5e6 very few curves would find it.[/QUOTE]

That's right.

[CODE]
Run 76 out of 250:
Using B1=11000000, B2=35133391030, polynomial Dickson(12), sigma=2937282173
Step 1 took 50670ms
Step 2 took 19890ms
********** Factor found in step 2: 24991157461902436638364677738700981780530893
Found probable prime factor of 44 digits: 24991157461902436638364677738700981780530893
Probable prime cofactor 770133409328510593934098647054112348863648709974876203302121061034340674324233272425893132240154136634104602673 has 111 digits
[/CODE]

Partway through 4000 curves at 11M, this popped out.

Good one.

a c134 so far

Who's this SB that is submitting all these curves??

Maybe SB = Serge Batalov?

correct