A171253 Semi-sums (average) of any two distinct Mersenne primes (A000668).

5, 17, 19, 65, 67, 79, 4097, 4099, 4111, 4159, 65537, 65539, 65551, 65599, 69631, 262145, 262147, 262159, 262207, 266239, 327679, 1073741825, 1073741827, 1073741839, 1073741887, 1073745919, 1073807359, 1074003967

Offset

1,1

Comments

Subsequence of A171252, excluding the terms of A000668 itself.

Links

Table of n, a(n) for n=1..28.

Jonathan Vos Post, Sums of three Mersenne primes, and prime sums of three Mersenne primes, SeqFan list, Mar 5, 2010.

Formula

a(n) = A171252(A014132(n)).

A171253 = A171252 \ A000688.

Example

a(1) = (A000668(2)+A000668(1))/2, a(2) = (A000668(3)+A000668(1))/2, a(3) = (A000668(3)+A000668(2))/2, a(4) = (A000668(4)+A000668(1))/2, ,...

Prog

(PARI) concat(vector(#A000668, i, vector(i-1, j, A000668[i]+A000668[j])))/2 /* having defined A000668 as vector with initial terms of A000668 */

Crossrefs

Cf. A171252 (includes terms of A000668), A171255 (primes in this sequence).

Sequence in context: A019401 A217079 A153320 * A226623 A171255 A304540

Adjacent sequences: A171250 A171251 A171252 * A171254 A171255 A171256

Keyword

nonn,changed

Author

M. F. Hasler, Mar 06 2010

Status

approved