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Old 2014-08-18, 02:41   #1
pdazzl
 
Apr 2014

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Default 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 P-1 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).
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Old 2014-08-18, 03:46   #2
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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 P-1 probability calculator to look into the P-1 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 P-1 started soon enough.

Last fiddled with by TheMawn on 2014-08-18 at 03:48
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Old 2014-08-18, 03:59   #3
pdazzl
 
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Go for it, I'm done done factoring on it. I TF'd it up 69.
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Old 2014-08-18, 04:09   #4
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Alright.

GTX 660 Ti: Factor=N/A,7508981,69,74
GTX 670: Factor=N/A,7508981,74,75
i5-3570k: Pminus1=N/A,1,2,7508981,-1,22049594,683537414

The P-1 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!
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Old 2014-08-18, 04:54   #5
axn
 
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Quote:
Originally Posted by TheMawn View Post
i5-3570k: Pminus1=N/A,1,2,7508981,-1,22049594,683537414
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 2014-08-18 at 04:56
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Old 2014-08-18, 05:16   #6
pdazzl
 
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Quote:
Originally Posted by axn View Post
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)?
@axn

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 P-1 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"
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Old 2014-08-18, 05:52   #7
TheMawn
 
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Quote:
Originally Posted by axn View Post
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)?
Good call. I just paste them in as inputs like in pdazzl's post?

I just used the ones that came out when I started looking. I used a round number for the probability of success.
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Old 2014-08-18, 07:07   #8
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Quote:
Originally Posted by pdazzl View Post
@axn

Pminus1=1,2,7508981,-1,1000,1000000000,"45053887,60071849,285341279,585700519,26356523311,20333239254737,18694135089678809,281287549065522023,346309182073938289,367107436768162151"
Sorry if this is a bit off topic.

Can this be done for cudapm1 as well?
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Old 2014-08-18, 08:47   #9
axn
 
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Quote:
Originally Posted by TheMawn View Post
I just paste them in as inputs like in pdazzl's post?
Yes.
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Old 2014-08-18, 11:07   #10
pdazzl
 
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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 :)
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Old 2014-08-18, 14:12   #11
R.D. Silverman
 
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Quote:
Originally Posted by pdazzl View Post
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
And?

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 2014-08-18 at 14:13 Reason: forgot to delete some stuff
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