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-   -   Absurdly good luck (https://www.mersenneforum.org/showthread.php?t=24687)

fivemack 2019-08-14 06:39

Absurdly good luck
 
Running 6000 @ B1=43e6 on L2478 (first 200-digit GNFS Fibonacci candidate), I found

[code]
e.29-Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=1:1188519769
e.29-Step 1 took 207383ms
e.29-Step 2 took 68344ms
e.29:********** Factor found in step 2: 7740375762651336047538103935179757607279716887642863845587
e.29:Found prime factor of 58 digits: 7740375762651336047538103935179757607279716887642863845587
e.29:Composite cofactor 10570991579334623840482883755513365612144723900388947995490841123880251343344547740058967903530860293469387580044622280139653686309968085494163 has 143 digits
[/code]

[b]and[/b]

[code]
e.37-Using B1=43000000, B2=240490660426, polynomial Dickson(12), sigma=1:86357729
e.37-Step 1 took 259895ms
e.37-Step 2 took 71127ms
e.37:********** Factor found in step 2: 275164049093203129870538695643000804660151573527986610243
e.37:Found prime factor of 57 digits: 275164049093203129870538695643000804660151573527986610243
e.37:Composite cofactor 297362418083032286913662831831249072357969201897330861036030388310680281063393526041488384532075349989927289101563373124395980680567961071896867 has 144 digits
[/code]

This completes what would otherwise have been a long factorisation.

I've informed Marin; I get the impression I've been quite implausibly lucky here

I'm posting mostly to have the sigma values recorded; they are 1: sigma values from gmp-7.1 and so factordb.com won't accept them.

GP2 2019-08-14 07:40

The limits you're using correspond to t=50 with 8704 curves, so it is pretty implausible to find both a 57-digit and a 58-digit factor, yes.


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