20030715, 01:54  #1 
Jun 2003
2^{2}×61 Posts 
trial factoring of "small" mersenne numbers
i noticed that there are many "small" mersenne numbers that have only been trial divided upto 57 bits. (decomp w 1 100000) for example. I tried to trial factor them (upto 58 bits) just for the heck of it but prime95 wouldnt let me. It said it was a bad factoring assignment. Anyone know why this is happening? Thanks.

20030715, 05:00  #2 
Aug 2002
Richland, WA
2^{2}×3×11 Posts 
I believe you need to set FactorOverride=58 in prime.ini .
The reason you get "bad factoring assignment" is that default factoring depth for an exponent around 1 million is much lower than 57 bits, so Prime95 doesn't think there is any work to do on the exponent. 
20030715, 05:40  #3  
"Richard B. Woods"
Aug 2002
Wisconsin USA
2^{2}·3·641 Posts 
Re: trial factoring of "small" mersenne numbers
Quote:


20030715, 11:50  #4 
Dec 2002
Frederick County, MD
562_{8} Posts 
Also, reference this post for another reason you shouldn't TF the smaller numbers.
http://www.mersenneforum.org/viewtopic.php?t=415 
20030715, 16:56  #5 
Jun 2003
F4_{16} Posts 
wow, thanks for all the replies. i did set factoroverride, but i had no idea that it takes longer to trial factor smaller numbers. I wasn't really planning on trial factoring those numbers since an first time LL and a double check were already performed on these numbers. I was just wondering why prime95 wouldn't even let me do it.

20030715, 17:50  #6 
Aug 2002
Richland, WA
2^{2}×3×11 Posts 
I just tested to make sure and it does work. I randomly chose 944821 from the nofactor file. My worktodo.ini has Factor=944821,57 and I set FactorOverride=58 in prime.ini . Make certain to restart Prime95 after making changes to prime.ini .

20030716, 23:35  #7 
Jun 2003
2^{2}×61 Posts 
i have only tested it upto 100,000. I havent bothered trying to trial factor anything above that. :)

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