20200120, 07:33  #1915 
Jun 2015
Vallejo, CA/.
3×383 Posts 

20200120, 20:52  #1916 
Dec 2011
After milion nines:)
2^{3}×7×29 Posts 

20200202, 01:07  #1917 
Random Account
Aug 2009
Not U. + S.A.
2×31×41 Posts 
1901*2^1958701 is prime! (58967 decimal digits)
It is not much but it is a start, once I determined how to use NewPGen. 
20200202, 07:10  #1918  
"Curtis"
Feb 2005
Riverside, CA
13013_{8} Posts 
Quote:
Also, newpgen is very very slow for this form of prime. The srsieve family of programs is an order of magnitude or so faster; srsieve to create the sieve initially, then sr1sieve to sieve a single "k" of k*2^n1. If you're interested in multiple k's, sr2sieve is your hero. sr1sieve speaks the same format as newpgen, so you can also use newpgen to create a sieve file, and then use sr1sieve to find factors. I forget if it's 10x or 20x faster, but it's really really fast. Command line, though all the good stuff is, around here. Have a look at https://www.rieselprime.de/default.htm to see what primes are known for individual k's. For 1901, that's 2, 62, 66, 210, 290, 602, 726, 938, 998, 21342, 195870, 239030, 335018. Last fiddled with by VBCurtis on 20200202 at 07:17 Reason: added prime list reference 

20200202, 14:38  #1919  
Random Account
Aug 2009
Not U. + S.A.
2·31·41 Posts 
Quote:
Quote:


20200206, 02:47  #1920 
Sep 2002
Database er0rr
2^{4}·281 Posts 
69*2^66399711 is prime! (1998833 decimal digits) Time : 2777.921 sec.
This prime has taken many years for Vincent and me to find, but, oh boy, is it worth it! Last fiddled with by paulunderwood on 20200206 at 07:29 
20200206, 08:02  #1921  
Sep 2006
The Netherlands
2×13×31 Posts 
Quote:


20200206, 09:04  #1922 
"Carlos Pinho"
Oct 2011
Milton Keynes, UK
7×733 Posts 
Congrats to both, well deserved.

20200206, 09:45  #1923 
Feb 2003
2^{7}×3×5 Posts 
Congratulations!
So close to 2 million decimal digits... 
20200206, 09:54  #1924 
Sep 2006
The Netherlands
1100100110_{2} Posts 
If there is 1+ closeby we'll have it soon as well.
69 seems very unpredictable now because of the huge gap, yet odds are they group a little together. 
20200206, 11:50  #1925 
Dec 2011
After milion nines:)
2^{3}×7×29 Posts 

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