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Old 2020-01-20, 07:33   #1915
rudy235
 
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Quote:
Originally Posted by Thomas11 View Post
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.
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Old 2020-01-20, 20:52   #1916
pepi37
 
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Quote:
Originally Posted by Thomas11 View Post
283*2^6804731-1 (2048431 digits)
Congratulations!
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Old 2020-02-02, 01:07   #1917
storm5510
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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.
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Old 2020-02-02, 07:10   #1918
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Quote:
Originally Posted by storm5510 View Post
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
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Old 2020-02-02, 14:38   #1919
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Quote:
Originally Posted by VBCurtis View Post
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 View Post
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.
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Old 2020-02-06, 02:47   #1920
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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
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Old 2020-02-06, 08:02   #1921
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Quote:
Originally Posted by paulunderwood View Post
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!!!
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Old 2020-02-06, 09:04   #1922
pinhodecarlos
 
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Congrats to both, well deserved.
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Old 2020-02-06, 09:45   #1923
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Congratulations!

So close to 2 million decimal digits...
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Old 2020-02-06, 09:54   #1924
diep
 
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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.
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Old 2020-02-06, 11:50   #1925
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Quote:
Originally Posted by diep View Post
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?
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