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A123214
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Primes q such that (2^p + 1)/3 is prime, where p = Prime[q]; or primes in A123176[n].
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1
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2, 3, 5, 7, 11, 31, 43, 1697, 12923, 13103, 77509
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OFFSET
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1,1
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COMMENTS
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A123176[n] are the numbers n such that (2^p + 1)/3 is prime, where p = Prime[n]. A123176[n] = PrimePi[A000978[n]]. PrimePi[a(n)] = {1,2,3,4,5,11,14,265,1540,1559,...}.
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LINKS
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EXAMPLE
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A123176[n] begin {2, 3, 4, 5, 6, 7, 8, 9, 11, 14, 18, 22, 26, 31, 39, 43, ...}.
Thus
a(1) = 2, a(2) = 3, a(3) = 5, a(4) = 7, a(5) = 11, a(6) = 31, a(7) = 43.
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CROSSREFS
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KEYWORD
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hard,more,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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