mersenneforum.org Post Lots and Lots of Top-5000 Primes Here
 Register FAQ Search Today's Posts Mark Forums Read

2020-01-20, 07:33   #1915
rudy235

Jun 2015
Vallejo, CA/.

3×383 Posts

Quote:
 Originally Posted by Thomas11 283*2^6804731-1 (2048431 digits)
Great Start of the Year!

Last year (2019) we had to wait 60 days more to get a prime over 2 million digits.

2020-01-20, 20:52   #1916
pepi37

Dec 2011
After milion nines:)

23×7×29 Posts

Quote:
 Originally Posted by Thomas11 283*2^6804731-1 (2048431 digits)
Congratulations!

 2020-02-02, 01:07 #1917 storm5510 Random Account     Aug 2009 Not U. + S.A. 2×31×41 Posts 1901*2^195870-1 is prime! (58967 decimal digits) It is not much but it is a start, once I determined how to use NewPGen.
2020-02-02, 07:10   #1918
VBCurtis

"Curtis"
Feb 2005
Riverside, CA

130138 Posts

Quote:
 Originally Posted by storm5510 1901*2^195870-1 is prime! (58967 decimal digits) It is not much but it is a start, once I determined how to use NewPGen.
You should use the "post small primes... here" thread for primes smaller than the top-5000 list cutoff, presently in the vicinity of 2^1.4M.

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^n-1. 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 2020-02-02 at 07:17 Reason: added prime list reference

2020-02-02, 14:38   #1919
storm5510
Random Account

Aug 2009
Not U. + S.A.

2·31·41 Posts

Quote:
 Originally Posted by VBCurtis You should use the "post small primes... here" thread for primes smaller than the top-5000 list cutoff, presently in the vicinity of 2^1.4M...
Done. There has been no activity on that thread since 2017, until now.

Quote:
 Originally Posted by VBCurtis 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^n-1. 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.
I would like to take a look at these. I will look around for them.

 2020-02-06, 02:47 #1920 paulunderwood     Sep 2002 Database er0rr 24·281 Posts 69*2^6639971-1 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 2020-02-06 at 07:29
2020-02-06, 08:02   #1921
diep

Sep 2006
The Netherlands

2×13×31 Posts

Quote:
 Originally Posted by paulunderwood 69*2^6639971-1 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!
3x HURRAY!!!

 2020-02-06, 09:04 #1922 pinhodecarlos     "Carlos Pinho" Oct 2011 Milton Keynes, UK 7×733 Posts Congrats to both, well deserved.
 2020-02-06, 09:45 #1923 Thomas11     Feb 2003 27×3×5 Posts Congratulations! So close to 2 million decimal digits...
 2020-02-06, 09:54 #1924 diep     Sep 2006 The Netherlands 11001001102 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.
2020-02-06, 11:50   #1925
pepi37

Dec 2011
After milion nines:)

23×7×29 Posts

Quote:
 Originally Posted by diep 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.
What was last prime in that sequence?

 Similar Threads Thread Thread Starter Forum Replies Last Post Viliam Furik Hardware 7 2020-09-27 22:27 TheMawn Software 18 2014-08-16 03:54 lsoule Riesel Prime Search 1999 2010-03-17 22:33 Peter Hackman Factoring 2 2008-08-15 14:26 jasong Information & Answers 4 2007-10-04 20:40

All times are UTC. The time now is 09:50.

Wed Feb 8 09:50:31 UTC 2023 up 174 days, 7:19, 1 user, load averages: 0.62, 0.88, 0.89