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2012-03-24, 15:00   #78
sascha77

Jan 2010
germany

2·13 Posts

Quote:
 Originally Posted by science_man_88 2*m*p+1 | 2^p-1 so really all your asking is can 2*m*p+1 divide 2 Mersennes but with only one p m=k*p is what you can check for.

Sorry. But I do not quite understand what you mean.
Can you give me an example ?

2012-03-24, 15:10   #79
science_man_88

"Forget I exist"
Jul 2009
Dartmouth NS

841810 Posts

Quote:
 Originally Posted by sascha77 "...so really all your asking is can 2*m*p+1 divide 2 Mersennes" Sorry. But I do not quite understand what you mean. Can you give me an example ?

2*m*p+1 ; m=k*p does 2*m*p+1 | 2^p-1 replace p with q in m=k*p and we have the 2 Mersennes problem talked about before.

Last fiddled with by science_man_88 on 2012-03-24 at 15:12

 2012-03-24, 20:37 #80 Dubslow Basketry That Evening!     "Bunslow the Bold" Jun 2011 40
2012-03-25, 03:31   #81
ATH
Einyen

Dec 2003
Denmark

19·181 Posts

Quote:
 Originally Posted by sascha77 Is it possible to chose p and k as descibed in (1) and (2), so that $2*k*p^{2}+1$ is prime and satisfies the congruence: $2^p \equiv 1 \;\;(\;mod\; 2*k*p^{2}+1\;)$
Works with: p=93077, k=674487

http://www.mersenne.org/report_expon...&B1=Get+status

 2012-03-25, 04:46 #82 Dubslow Basketry That Evening!     "Bunslow the Bold" Jun 2011 40
2012-03-26, 05:44   #83
ATH
Einyen

Dec 2003
Denmark

19·181 Posts

Quote:
 Originally Posted by Dubslow ATH, how did you find it that fast?
I had a text file with a lot of GIMPS factors lying around and I just made a program to quickly check if factor-1 = 0 (mod p^2).

I now downloaded, I think, the entire GIMPS factor database: 33,545,802 factors up to p=1,000,000,000, and there is NO other example besides p=93077, so this seems to be very rare indeed.

All factors of mersenne numbers are of the form 2kp+1, so this case is when k happens to be a multiple of p as well: k=c*p.

Last fiddled with by ATH on 2012-03-26 at 05:44

 2012-03-26, 05:46 #84 Dubslow Basketry That Evening!     "Bunslow the Bold" Jun 2011 40
2012-03-26, 07:22   #85
kar_bon

Mar 2006
Germany

3·7·11·13 Posts

Quote:
 Originally Posted by Dubslow How exactly did you download all the factors?
See Will Edington's page, for example (middle of the page as *.bz2-files).

2012-03-26, 09:09   #86
ATH
Einyen

Dec 2003
Denmark

D6F16 Posts

Quote:
 Originally Posted by Dubslow Hmm... James' site goes beyond 1B, and there are definitely some factors know greater than M3.32B... How exactly did you download all the factors?
I created a script that downloaded them in chunks from the server here:
http://www.mersenne.org/report_facto...B1=Get+Factors

If you want the factors you can get them from me, so we don't strain the database again for the same factors.

2012-03-26, 19:12   #87
sascha77

Jan 2010
germany

2×13 Posts

Quote:
 Originally Posted by ATH I created a script that downloaded them in chunks from the server here: http://www.mersenne.org/report_facto...B1=Get+Factors If you want the factors you can get them from me, so we don't strain the database again for the same factors.

Great work !!!
I wanted today to check manually all the factors from the http://mersenne-aries.sili.net site. But you and Dubslow were faster and really found a counterexample. Great.
ATH: Can you send the file with the factors to me also ?

2012-03-26, 21:16   #88
Dubslow

"Bunslow the Bold"
Jun 2011
40<A<43 -89<O<-88

722110 Posts

Quote:
 Originally Posted by ATH I created a script that downloaded them in chunks from the server here: http://www.mersenne.org/report_facto...B1=Get+Factors If you want the factors you can get them from me, so we don't strain the database again for the same factors.
Ah, I didn't realize PrimeNet had a known factors report. I was thinking you wrote a script to parse the report_exponent, but that seemed like a lot of effort

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