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#12 |
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"NOT A TROLL"
Mar 2016
California
3058 Posts |
That is the only exception:
2^p+p^2 is prime, so p is an odd multiple of 3: Case 1: p = 1 (mod 3): 2^p+p^2 = 0 (mod 3); 2 (mod 3) + 1 (mod 3) = 0 (mod 3) Case 2: p = 2 (mod 3): 2^p+p^2 = 0 (mod 3); 2 (mod 3) + 1 (mod 3) = 0 (mod 3) Case 3: p = 0 (mod 3): 2^p+p^2 = 2 (mod 3); 2 (mod 3) + 0 (mod 3) = 2 (mod 3) See, I was correct. |
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#13 |
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"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
100101000001012 Posts |
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#14 |
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"99(4^34019)99 palind"
Nov 2016
(P^81993)SZ base 36
5×7×83 Posts |
See http://www.primenumbers.net/Henri/us/NouvP1us.htm, there are also no known primes of these forms:
(2^n-k)*2^n+1, for k = 7, 34, 74, 79, ... and is 3 the only n such that (2^n-k)*2^n+1 is prime for k=6? (if (2^n-k)*2^n+1 is prime for k=1, then this n must be 3-smooth) (2^n+k)*2^n+1 for k = 15. (if (2^n+k)*2^n+1 is prime for k=1, then this k must be a power of 3) Besides, for (2^n-k)*2^n-1 and (2^n+k)*2^n-1, is there any reserving for them? Last fiddled with by sweety439 on 2017-01-21 at 11:54 |
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