

A123176


Numbers n such that (2^p + 1)/3 is prime, where p is the nth prime.


2



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
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OFFSET

1,1


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.


LINKS

Table of n, a(n) for n=1..41.
C. Caldwell's The Top Twenty, Wagstaff.


FORMULA

a(n) = A000720( A000978(n) ).


CROSSREFS

Cf. A000978, A000979, A001045, A049883, A107036, A123214.
Sequence in context: A082324 A219955 A079064 * A017902 A005710 A291146
Adjacent sequences: A123173 A123174 A123175 * A123177 A123178 A123179


KEYWORD

more,nonn


AUTHOR

Alexander Adamchuk, Oct 03 2006


EXTENSIONS

Two more terms computed from A000978 by Max Alekseyev, Mar 03 2010


STATUS

approved



