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Search: id:A123214
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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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OFFSET
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1,1
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COMMENT
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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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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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Cf. A123176, A000978, A000979, A001045, A049883, A107036.
Sequence in context: A155833 A028867 A104154 this_sequence A119834 A095180 A101989
Adjacent sequences: A123211 A123212 A123213 this_sequence A123215 A123216 A123217
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KEYWORD
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hard,more,nonn
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AUTHOR
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Alexander Adamchuk (alex(AT)kolmogorov.com), Oct 05 2006
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