fond of a factor? Urn yourself to become inane - Page 162

James Heinrich · 2021-01-21, 20:28

Quote:

Originally Posted by storm5510

I too have found a 39-digit factor... I never checked on any list to see if it was there.

It's #385 on the biggest ECM factors (edit: of Mersenne numbers) list.

LaurV · 2021-01-22, 07:18

Quote:

Originally Posted by James Heinrich

It's #385 on the biggest ECM factors list for mersenne numbers.

Fixed it for you. As opposite to biggest ever, openweight.

Jwb52z · 2021-01-23, 18:15

P-1 found a factor in stage #2, B1=737000, B2=19917000.
UID: Jwb52z/Clay, M102307399 has a factor: 376759813552401417250697953 (P-1, B1=737000, B2=19917000),

88.284 bits.

storm5510 · 2021-01-23, 18:20

Quote:

Originally Posted by James Heinrich

It's #385 on the biggest ECM factors (edit: of Mersenne numbers) list.

Thank you for the link. 70 digits at the top. That is quite amazing.

Jwb52z · 2021-01-27, 02:58

P-1 found a factor in stage #2, B1=738000, B2=19926000.
UID: Jwb52z/Clay, M102357631 has a factor: 321965205924875189306321369 (P-1, B1=738000, B2=19926000),

88.057 bits.

gLauss · 2021-01-27, 07:43

I found a very easy one (randomly selected a nice number and spent <1 GhzD effort) in M3331331 yesterday, but the number was factored previously: mersenne.ca, Primenet Details. What bothers me is that the same PRP residue is identical for the PRP test with 1 factor and the PRP test with 2 factors? This is a bug, isn't it?

The factor I'm most proud of is this lucky 118bit one in M70553939 which I found in normal LL/PRP testing.

LaurV · 2021-01-27, 08:00

Quote:

Originally Posted by gLauss

This is a bug, isn't it?

Yep. Bug for sure, unless you used gpuowl, which totally ignores the factors, and does prp for the whole Mxx, in which case both residues (and the semantic result, like the cofactor being PRP or not) are wrong. Right now, only P95/mprime can be used for PRP-CF and PRP-CF-DC. If you use gpuowl, it will not signal an error, but it will PRP the wrong number. I assume Mihai is working on this, either to include the PRP-CF option, or to give and error when worktodo line contains factors.

gLauss · 2021-01-27, 08:16

Quote:

Originally Posted by LaurV

Yep. Bug for sure,

I used mprime and the residue B786DF1732AE7343 is the one which mprime reported in the results.json.txt. I filed a bug in the Primenet section.

axn · 2021-01-27, 08:46

Quote:

Originally Posted by LaurV

Yep. Bug for sure

No. P95 calculates 3^(Mp+1) == 3^(f+1) to prp test Mp/f. So the residue produced is always the same.

By calculating 3^(Mp+1), you can just do repeated squaring (more efficient), which also allows GEC / CERT capability.

kruoli · 2021-01-27, 09:11

Quote:

Originally Posted by gLauss

The factor I'm most proud of is this lucky 118bit one in M70553939 which I found in normal LL/PRP testing.

It looks like Brent-Suyama helped you there.

James Heinrich · 2021-01-27, 16:46

Quote:

Originally Posted by axn

No. P95 calculates 3^(Mp+1) == 3^(f+1) to prp test Mp/f. So the residue produced is always the same.
By calculating 3^(Mp+1), you can just do repeated squaring (more efficient), which also allows GEC / CERT capability.

Does this mean one could fake the residue for a PRP test with a different number of cofactors (trivial, it's always the same), but one would not be able to (so easily) fake the proof?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
A new factor of F11?!	siegert81	FermatSearch	2	2018-01-24 04:35
AMD goes inane	jasong	jasong	18	2013-11-15 22:54
A fond farewell	rogue	Lounge	10	2008-11-21 05:25
P56 ECM Factor	wblipp	Factoring	4	2005-04-23 11:41
Shortest time to complete a 2^67 trial factor (no factor)	dsouza123	Software	12	2003-08-21 18:38

2021-01-23, 18:15	#1774
Jwb52z Sep 2002 5×157 Posts	P-1 found a factor in stage #2, B1=737000, B2=19917000. UID: Jwb52z/Clay, M102307399 has a factor: 376759813552401417250697953 (P-1, B1=737000, B2=19917000), 88.284 bits.

2021-01-27, 02:58	#1776
Jwb52z Sep 2002 5×157 Posts	P-1 found a factor in stage #2, B1=738000, B2=19926000. UID: Jwb52z/Clay, M102357631 has a factor: 321965205924875189306321369 (P-1, B1=738000, B2=19926000), 88.057 bits.

2021-01-27, 07:43	#1777
gLauss Nov 2014 2³·3 Posts	I found a very easy one (randomly selected a nice number and spent <1 GhzD effort) in M3331331 yesterday, but the number was factored previously: mersenne.ca, Primenet Details. What bothers me is that the same PRP residue is identical for the PRP test with 1 factor and the PRP test with 2 factors? This is a bug, isn't it? The factor I'm most proud of is this lucky 118bit one in M70553939 which I found in normal LL/PRP testing.