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Old 2013-09-25, 01:11   #936
3.14159
 
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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)
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Old 2013-09-30, 16:59   #937
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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)
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Old 2013-09-30, 21:19   #938
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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)
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Old 2013-12-31, 15:24   #939
firejuggler
 
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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
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Old 2014-01-07, 09:28   #940
gd_barnes
 
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Quote:
Originally Posted by firejuggler View Post
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
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Old 2014-04-14, 18:18   #941
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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.
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Old 2014-05-26, 23:45   #942
Trilo
 
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"W. Byerly"
Aug 2013
1423*2^2179023-1

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Quote:
Originally Posted by lorgix View Post
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!
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Old 2014-11-29, 06:02   #943
TheCount
 
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Sep 2013
Perth, Au.

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Smile Compositorial primes

Found some new Compositorial primes:
15250!/15250#-1
17258!/17258#+1
How can I figure out the decimal length?
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Old 2014-11-29, 06:19   #944
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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
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Old 2015-07-11, 13:16   #945
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1224323*2^1048321+1 is prime.
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Old 2015-07-26, 21:43   #946
Stargate38
 
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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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