20110318, 20:11  #1 
Mar 2007
Austria
12E_{16} Posts 
Probability of factor (TF)
Hi,
Is there a formula / excel spreadsheet anywhere which lets me calculate the probablility that I find a factor for Mn by trial factoring from x to x+1 bits, with no previously known factor? Thanks, nugget 
20110318, 21:28  #2  
Account Deleted
"Tim Sorbera"
Aug 2006
San Antonio, TX USA
17×251 Posts 
http://mersennearies.sili.net/credit.php (put in a TF assignment and factoring range, as part of the result it says the chance of finding a factor)
That's the easiest way, since it applies the formula for you. The actual formula is at: http://www.mersenne.org/various/math.php Quote:
But note that this only counts starting at about log_2(p) bits, since all factors must be of the form 2kp+1. Whether there is a previously known factor does not make a difference in the distribution of further factors, but the TF depth does. Last fiddled with by MiniGeek on 20110318 at 21:32 

20110319, 22:14  #3  
Jun 2003
7·167 Posts 
Quote:
Last fiddled with by Mr. P1 on 20110319 at 22:14 

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