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Search: id:A139428
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| A139428 |
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Smallest prime p such that M(n)^2-p*M(n)-1 is prime with M(n)= Mersenne primes =A000668(n). |
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+0
8
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| 5, 7, 5, 17, 43, 67, 41, 53, 311, 317, 317, 43, 1427, 37, 25693, 563, 17239, 911, 11497, 112247, 1259, 190639, 138569, 296713, 27733, 11777
(list; graph; listen)
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OFFSET
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2,1
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COMMENT
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All primes certified using openpfgw_v12 from primeform group
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EXAMPLE
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7*7-5*7-1=13 prime 7=M(2)=2^3-1 so k(2)=5
31*31-7*31-1=743 prime 31=M(3)=2^5-1 so k(3)=7
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CROSSREFS
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Cf. A000668, A139424, A139425, A139426, A139427, A139429, A139430, A139421.
Sequence in context: A109353 A121595 A125294 this_sequence A063005 A145577 A144478
Adjacent sequences: A139425 A139426 A139427 this_sequence A139429 A139430 A139431
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KEYWORD
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hard,more,nonn
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AUTHOR
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Pierre CAMI (pierrecami(AT)tele2.fr), Apr 21 2008
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