1,1

A000043 INTERSECT A007510.

For the isolated prime p=2= A007510(1), p^2-1=3 is prime, which adds p=2 to the sequence.

MP := [2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607, 1279, 2203, 2281, 3217, 4253, 4423, 9689, 9941, 11213, 19937, 21701, 23209, 44497, 86243, 110503, 132049, 216091, 756839, 859433, 1257787, 1398269, 2976221, 3021377, 6972593, 13466917]:

n := 0: for j to 39 do if `and`(isprime(MP[j]-2) = false, isprime(MP[j]+2) = false) then n := n+1; a[n] := MP[j] else end if end do:

seq(a[n], n = 1 .. 25); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 20 2009]

Cf. A000043, A007510.

Sequence in context: A058459 A105268 A139881 this_sequence A023302 A041967 A024239

Adjacent sequences: A161673 A161674 A161675 this_sequence A161677 A161678 A161679

nonn

Vladislav-Stepan Malakhovsky & Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Jun 16 2009

More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 20 2009

Definition rephrased by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 23 2009