Help need to running Msieve - Page 2

wombatman · 2016-04-07, 04:00

Glad it worked! As for why it found the factor so quickly, it appears to be doing a P-1 factoring check. Maybe Jason can confirm that this is correct?

If you use factordb.com (http://factordb.com/index.php?query=...439041076399-1), you can see that the P47 factor, when you subtract one, is composed entirely of very small factors, making it a good candidate to be found by the P-1 method.

Basically, msieve found a quick factor instead of actually going through the full NFS process.

jasonp · 2016-04-10, 02:31

A P47 that can be found by P-1 with such small bounds is so unlikely to occur by chance that I would suspect such numbers are deliberately constructed.

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2016-04-07, 04:00	#12
wombatman I moo ablest echo power! May 2013 3351₈ Posts	Glad it worked! As for why it found the factor so quickly, it appears to be doing a P-1 factoring check. Maybe Jason can confirm that this is correct? If you use factordb.com (http://factordb.com/index.php?query=...439041076399-1), you can see that the P47 factor, when you subtract one, is composed entirely of very small factors, making it a good candidate to be found by the P-1 method. Basically, msieve found a quick factor instead of actually going through the full NFS process.

2016-04-10, 02:31	#13
jasonp Tribal Bullet Oct 2004 3541₁₀ Posts	A P47 that can be found by P-1 with such small bounds is so unlikely to occur by chance that I would suspect such numbers are deliberately constructed.