20160406, 19:05  #1 
Sep 2013
70_{8} Posts 
PRP in A138957
There were some posts about https://oeis.org/A007908, so in case
someone is interested in https://oeis.org/A138957 too: I got the 7816th term PRP, 30157 digits. It would be nice if someone could doublecheck. I went up to 39999 without another hit, so no other PRPs up to 70Kth term. 
20160406, 19:49  #2 
Sep 2002
Database er0rr
3,491 Posts 
Attach the decimal expansion in a file and I will check it out for you.

20160406, 20:15  #3  
Sep 2013
70_{8} Posts 
Quote:
qualify as valid doublecheck? 

20160406, 20:29  #4 
Sep 2002
Database er0rr
3,491 Posts 
For each a in {0,3,4,5,6,7} jacobiSymbol(a^24,n)==1 and (x+a)^(n+1)==5+2*a (mod n, x^2a*x+1)., which implies EulerPRP tests base 5+2*a and associated Lucas PRP tests.
Congrats on something that is almost certainly prime, modulo an ECPP check. Maybe you missed a PRP .... Last fiddled with by paulunderwood on 20160406 at 20:46 
20160406, 20:56  #5 
Sep 2013
38_{16} Posts 
What I meant is, yes, the number in the file is a PRP, but is it the 'right' number?
For instance, bug in my string generation. A doublechecker should use its own. 
20160406, 21:10  #6 
Sep 2002
Database er0rr
3,491 Posts 
Code:
? v=[];for(n=1,7816,d=digits(n);forstep(k=#d,1,1,v=concat(v,d[k])));JF=read("../../Downloads/781630157digits.txt");digits(JF)==v 1 Last fiddled with by paulunderwood on 20160406 at 21:11 
20160406, 21:22  #7 
Sep 2013
2^{3}·7 Posts 
Thanks!

20160406, 23:02  #8 
Sep 2002
Database er0rr
3,491 Posts 

20160407, 03:16  #9  
"Rashid Naimi"
Oct 2015
Remote to Here/There
793_{16} Posts 
Quote:
If so what sizes would be interesting? Thank you in advance. BTW that thread seems to be here: http://www.mersenneforum.org/showthr...695#post415695 Last fiddled with by a1call on 20160407 at 03:57 

20160407, 19:19  #10  
Aug 2006
13462_{8} Posts 
Quote:


20160407, 19:22  #11 
Sep 2002
Database er0rr
3,491 Posts 
http://www.primenumbers.net/prptop/p...p?page=40#haut
You can enter "page" beyond "40", so that the actual lower limit is now 20k digits for submissions. 