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 2013-09-25, 01:11 #936 3.14159     May 2010 Prime hunting commission. 24·3·5·7 Posts Bumping: 200662*3716450+1 (25803 digits) Primality testing 200662*37^16450+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 7 Special modular reduction using zero-padded AMD K10 type-0 FFT length 10K, Pass1=40, Pass2=256 on 200662*37^16450+1 Calling Brillhart-Lehmer-Selfridge with factored part 99.98% 200662*37^16450+1 is prime! (22.7424s+0.0059s)
 2013-09-30, 16:59 #937 3.14159     May 2010 Prime hunting commission. 24×3×5×7 Posts bumping yet again with some cofactor PRPs: ((8649*157+46)*2^17090+1)/157 ((9953*157+46)*2^17090+1)/157 ((12728*157+46)*2^17090+1)/157 52376*1012870+1 (12875 digits) Running N-1 test using base 3 Special modular reduction using all-complex FFT length 4K on 52396*10^12870+1 Calling Brillhart-Lehmer-Selfridge with factored part 69.87% 52396*10^12870+1 is prime! (20.8757s+0.0227s)
 2013-09-30, 21:19 #938 3.14159     May 2010 Prime hunting commission. 32208 Posts kbb-GFN: (14903*876876)^4+1 (10328 digits) Primality testing (14903*876^876)^4+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 5 Generic modular reduction using generic reduction FFT length 3584 on A 34307-bit number Calling Brillhart-Lehmer-Selfridge with factored part 63.22% (14903*876^876)^4+1 is prime! (8.4195s+0.0046s)
 2013-12-31, 15:24 #939 firejuggler     Apr 2010 Over the rainbow 1001111010012 Posts appropriatly for today Code: 31122013*2^56+1 31122013*2^57 + 3 is prime! (verification : a = 3) [25 digits] - Sophie Germain - 31122013*2^476+1 31122013*2^692+1 31122013*2^818+1 31122013*2^13178+1 31122013*2^40592+1 Last fiddled with by firejuggler on 2013-12-31 at 15:25
2014-01-07, 09:28   #940
gd_barnes

May 2007
Kansas; USA

33·383 Posts

Quote:
 Originally Posted by firejuggler appropriatly for today Code: 31122013*2^56+1 31122013*2^57 + 3 is prime! (verification : a = 3) [25 digits] - Sophie Germain - 31122013*2^476+1 31122013*2^692+1 31122013*2^818+1 31122013*2^13178+1 31122013*2^40592+1
Interestingly, 31122013*2^57 - 3 is also prime so we have:

31122013*2^56 + 1
31122013*2^57 + 3
31122013*2^57 - 3
are all prime

 2014-04-14, 18:18 #941 lorgix     Sep 2010 Scandinavia 3×5×41 Posts Code: Primality testing 1038990*2^1048320+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 11 Calling Brillhart-Lehmer-Selfridge with factored part 100.00% 1038990*2^1048320+1 is prime! (2165.2179s+0.0009s) I don't think this was known before. This is my largest find yet. Just outside of the top-5000, I believe.
2014-05-26, 23:45   #942
Trilo

"W. Byerly"
Aug 2013
1423*2^2179023-1

103 Posts

Quote:
 Originally Posted by lorgix Code: Primality testing 1038990*2^1048320+1 [N-1, Brillhart-Lehmer-Selfridge] Running N-1 test using base 11 Calling Brillhart-Lehmer-Selfridge with factored part 100.00% 1038990*2^1048320+1 is prime! (2165.2179s+0.0009s) I don't think this was known before. This is my largest find yet. Just outside of the top-5000, I believe.
Nice find!

 2014-11-29, 06:02 #943 TheCount     Sep 2013 Perth, Au. 9810 Posts Compositorial primes Found some new Compositorial primes: 15250!/15250#-1 17258!/17258#+1 How can I figure out the decimal length?
 2014-11-29, 06:19 #944 paulunderwood     Sep 2002 Database er0rr 2·33·67 Posts Code: ./pfgw64 -d -od -q'len(15250!/15250#-1)' -f0 PFGW Version 3.7.7.64BIT.20130722.x86_Dev [GWNUM 27.11] No factoring at all, not even trivial division len(15250!/15250#-1): 50623 Code: ./pfgw64 -d -od -q'len(17258!/17258#+1)' -f0 PFGW Version 3.7.7.64BIT.20130722.x86_Dev [GWNUM 27.11] No factoring at all, not even trivial division len(17258!/17258#+1): 58207
 2015-07-11, 13:16 #945 lorgix     Sep 2010 Scandinavia 3·5·41 Posts 1224323*2^1048321+1 is prime.
 2015-07-26, 21:43 #946 Stargate38     "Daniel Jackson" May 2011 14285714285714285714 23×34 Posts Here's some primes that I found (only primes >101000): 101954445583631786514*361516-1 101954445583631786514*361577-1 101954445583631786513*36653+1 101954445583631786513*36861+1 101954445583631786513*361464+1 101954445583631786513*364021+1 101954445583631786513*365571+1 I've actually found a lot more (2127 in total, including PRPs), but I don't want to spam the forums. Last fiddled with by Stargate38 on 2015-07-26 at 21:47

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