OFFSET
1,1
EXAMPLE
For the isolated prime p = 2 = A007510(1), p^2-1 = 3 is prime, which adds p = 2 to the sequence.
MAPLE
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); # Emeric Deutsch, Jun 20 2009
CROSSREFS
KEYWORD
nonn,more,changed
AUTHOR
Vladislav-Stepan Malakhovsky and Juri-Stepan Gerasimov, Jun 16 2009
EXTENSIONS
More terms from Emeric Deutsch, Jun 20 2009
Definition rephrased by R. J. Mathar, Sep 23 2009
a(26)-a(32) from Amiram Eldar, Oct 19 2024
STATUS
approved