20140818, 02:41  #1 
Apr 2014
7×17 Posts 
M7508981 has at least 12 prime factors(new factor # record)
http://www.mersenne.ca/exponent/7508981
M7508981 now has 10 known factors, the remaining cofactor PRP tested as not prime. Therefore it must have 12 or more prime factors (assuming the other 10 factor mersenne number 566448359's remaining cofactor is not PRP tested which it probably isn't). Top Mersenne exponents with the most known factors  page should update soon http://www.mersenne.ca/manyfactors.p...n=4&fac_max=10 Will finish TF'ing to 69 in <1 hour, there is still plenty of TF'ing that can be done and no P1 has been done yet either, if anyone wants to throw firepower at this exponent to see if more factors show up(factored this puppy with a GTS 450). 
20140818, 03:46  #2 
May 2013
East. Always East.
6BF_{16} Posts 
I'm willing to do both. I can't grab it as an assignment off mersenne.org or GPU72.com. Do you own the exponent?
I'm using the P1 probability calculator to look into the P1 bounds. With TF up to 75, with bounds B1=22049594 and B2=683537414, there's a 7.5% chance to find a factor with 18 GHzDays of work. The chance drops to 5% if the TF is done up to 80. EDIT: I misread the assignment as 75 million. It's actually 7.5 million, hence why is it unavailable for assignment. Would you like me to start right away? I can get TF from 69 to 74 on one GPU, and 74 to 75 on another, and the P1 started soon enough. Last fiddled with by TheMawn on 20140818 at 03:48 
20140818, 03:59  #3 
Apr 2014
7×17 Posts 
Go for it, I'm done done factoring on it. I TF'd it up 69.

20140818, 04:09  #4 
May 2013
East. Always East.
11×157 Posts 
Alright.
GTX 660 Ti: Factor=N/A,7508981,69,74 GTX 670: Factor=N/A,7508981,74,75 i53570k: Pminus1=N/A,1,2,7508981,1,22049594,683537414 The P1 will be done Tuesday evening. I imagine the factoring will be faster, although 74 to 75 for such a small exponent could take a while. I'll let you know if I find anything! 
20140818, 04:54  #5 
Jun 2003
2·3^{2}·269 Posts 
You should give the known factors also in there. Otherwise, it'll stop after stage 1 with one or more of the known factors found.
Also... Really weird bounds. Why not give some round numbers (like 25e6,1e9)? Last fiddled with by axn on 20140818 at 04:56 
20140818, 05:16  #6  
Apr 2014
7·17 Posts 
Quote:
I was not aware you could do that (thought it always kicked out after stage 1 if anything was found). I think I may do a P1 in tandem, a narrow B1 with a deep B2 Pminus1=1,2,7508981,1,1000,1000000000,"45053887,60071849,285341279,585700519,26356523311,20333239254737,18694135089678809,281287549065522023,346309182073938289,367107436768162151" 

20140818, 05:52  #7  
May 2013
East. Always East.
11·157 Posts 
Quote:
I just used the ones that came out when I started looking. I used a round number for the probability of success. 

20140818, 07:07  #8 
"Adolf"
Nov 2013
South Africa
61 Posts 

20140818, 08:47  #9 
Jun 2003
2×3^{2}×269 Posts 

20140818, 11:07  #10 
Apr 2014
7×17 Posts 
Thanks for everyone's help on this one, would be neat if more factors are found.
Who knows, maybe a +2M digit prime is at play here :) 
20140818, 14:12  #11  
Nov 2003
2^{2}×5×373 Posts 
Quote:
What is the punchline here? A number of this size will have, on average about 15.4 prime factors (with a standard deviation of about 3.93). What makes this worth discussing? Last fiddled with by R.D. Silverman on 20140818 at 14:13 Reason: forgot to delete some stuff 

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