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A123176
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Numbers n such that (2^p + 1)/3 is prime, where p is the n-th prime.
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1
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2, 3, 4, 5, 6, 7, 8, 9, 11, 14, 18, 22, 26, 31, 39, 43, 46, 65, 69, 126, 267, 380, 495, 762, 1285, 1304, 1364, 1479, 1697, 4469, 8135, 9193, 11065, 11902, 12923, 13103, 23396, 23642, 31850, 77509, 285228
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Also prime(a(n)) are the indices of prime Jacobsthal numbers (A001045) with prime indices. Primes in the Jacobsthal sequence are listed in A049883.
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LINKS
| C. Caldwell's The Top Twenty, Wagstaff.
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FORMULA
| a(n) = A000720( A000978(n) ).
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CROSSREFS
| Cf. A000978, A000979, A001045, A049883, A107036, A123214.
Sequence in context: A202940 A082324 A079064 * A017902 A005710 A023358
Adjacent sequences: A123173 A123174 A123175 * A123177 A123178 A123179
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KEYWORD
| more,nonn
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AUTHOR
| Alexander Adamchuk (alex(AT)kolmogorov.com), Oct 03 2006
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EXTENSIONS
| Two more terms computed from A000978 by Max Alekseyev (maxale(AT)gmail.com), Mar 03 2010
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