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2021-02-11, 06:55   #1959
Happy5214

"Alexander"
Nov 2008
The Alamo City

2·33·17 Posts

Quote:
 Originally Posted by Trilo 55*2^2048305-1 is prime! (627441 digits)
That range was already tested by Kosmaj. Luckily I found it on PrimePages. It's 55*2^2084305-1.

Last fiddled with by Happy5214 on 2021-02-11 at 06:55 Reason: Linking to PrimePages

 2021-03-06, 09:13 #1960 kuratkull     Mar 2007 Estonia 149 Posts Code: 195*2^4685711-1 is prime! (1410542 decimal digits) https://primes.utm.edu/primes/page.php?id=132121 k<300 highest Nash weight k delivers again.
2021-03-06, 19:32   #1961
pepi37

Dec 2011
After milion nines:)

3·541 Posts

Quote:
 Originally Posted by kuratkull Code: 195*2^4685711-1 is prime! (1410542 decimal digits) https://primes.utm.edu/primes/page.php?id=132121 k<300 highest Nash weight k delivers again.

Congratulations!

 2021-03-18, 08:38 #1962 gd_barnes     "Gary" May 2007 Overland Park, KS 2E2116 Posts 285*2^1801236-1 is prime
 2021-04-05, 17:41 #1963 VBCurtis     "Curtis" Feb 2005 Riverside, CA 3·1,877 Posts Been a while: 99*2^2658496-1 is prime! (800290 digits)
 2021-04-12, 05:34 #1964 gd_barnes     "Gary" May 2007 Overland Park, KS 72·241 Posts From the 3rd megabit drive: 257*2^2108554-1 is prime :-)
 2021-04-26, 16:40 #1965 gd_barnes     "Gary" May 2007 Overland Park, KS 72×241 Posts A pair from the 3rd megabit drive: 235*2^2163273-1 219*2^2178673-1
 2021-04-29, 20:22 #1966 kuratkull     Mar 2007 Estonia 149 Posts Code: 197*2^4765318-1 is prime! (1434506 decimal digits) https://primes.utm.edu/primes/page.php?id=132236
 2021-06-27, 11:11 #1967 gd_barnes     "Gary" May 2007 Overland Park, KS 72·241 Posts 21*2^2959789-1 is prime
 2021-09-07, 18:27 #1968 rudy235     Jun 2015 Vallejo, CA/. 3·383 Posts The largest prime for 2021 and 2nd largest since Christmas 2018 has been discovered. It is a 3 2 1 Prime i.e. 3*2k-1 The prime is 3*217748034 -1 and has 5342692 digits. This is the largest known prime for the 3*2^n-1 form. Currently it stands in position 18 overall and is the 6th Non-Mersenne prime in size. Congratulations to Mark Wiseler and the PrimeGrid group. Last fiddled with by VBCurtis on 2021-09-08 at 00:01 Reason: Fixed the "+1" to be the correct -1
2021-09-07, 21:48   #1969
slandrum

Jan 2021
California

10058 Posts

Quote:
 Originally Posted by rudy235 It is a 3 2 1 Prime i.e. 3*2k+1 The prime is 3*217748034 -1 and has 5342692 digits.
So, is it +1 or -1?

Edit: I can see that it's almost certainly the -1 form from the next line in the post, but it's still confusing with the first line contradicting it.

VBCurtis: I fixed the post.

Last fiddled with by VBCurtis on 2021-09-08 at 00:01

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