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A239741
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Numbers k such that prime(k) * 2^k - 1 is prime.
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2
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1, 2, 11, 24, 28, 92, 166, 191, 220, 587, 677, 964, 988, 1840, 2664, 3604, 6079, 6640, 8817, 33647, 34308, 39882, 44055, 47050, 64100, 103313, 223439, 225921
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OFFSET
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1,2
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COMMENTS
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The PFGW program has been used to certify all the terms up to a(28), using a deterministic test which exploits the factorization of a(n)+1.
a(29) > 290000.
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LINKS
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MATHEMATICA
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Select[Range[1000], PrimeQ[Prime[#]*2^# - 1] &]
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PROG
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(Magma) [n: n in [0..1000] | IsPrime(NthPrime(n)*2^n-1)]; // Vincenzo Librandi, Dec 24 2015
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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