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Search: id:A120364
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| A120364 |
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Primes p such that p^2-p-1 and p^2-p+1 are twin primes. |
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+0
1
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| 3, 7, 67, 139, 379, 457, 1201, 1381, 1549, 1567, 1747, 1789, 2137, 2557, 2647, 2731, 4057, 4159, 4447, 4561, 5179, 5641, 6397, 9157, 9661, 9829, 9967, 10369, 11467, 11677, 12487, 12781, 13339, 13399, 15241, 17299, 17977, 19207, 19417, 19429
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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3*3-3-1=5 3*3-3+1=7, 5 and 7 twin primes so a(1)=3
5*5-5-1=19 5*5-5+1=21 composite
7*7-7-1=41 7*7-7+1=43, 41 and 43 twin primes so a(2)=7
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MATHEMATICA
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Select[Prime[Range[2500]], PrimeQ[ #^2 - # - 1] && PrimeQ[ #^2 - # + 1] &] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jul 22 2006
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CROSSREFS
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Adjacent sequences: A120361 A120362 A120363 this_sequence A120365 A120366 A120367
Sequence in context: A134705 A110433 A041817 this_sequence A088797 A127177 A127179
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KEYWORD
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nonn
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AUTHOR
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Pierre CAMI (pierrecami(AT)tele2.fr), Jun 26 2006
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com) and Rick L. Shepherd (rshepherd2(AT)hotmail.com), Jul 22 2006
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