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A123176 Numbers n such that (2^p + 1)/3 is prime, where p is the n-th 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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 18 21:20 EST 2020. Contains 332028 sequences. (Running on oeis4.)