1,1

These are all primes of the form n!! + (n+1)!! Corresponding values of n are 0, 1, 2, 3, 4. At n>4, n!! + (n+1)!! is always composite, cf. A118333.

Apparently also the set of primes p(n) such that p(n)^2 - 2^n is prime. - Irina Gerasimova, May 09 2013

Table of n, a(n) for n=1..5.

Cf. A118333.

Sequence in context: A117221 A073879 A073880 * A118333 A131101 A188534

Adjacent sequences: A118329 A118330 A118331 * A118333 A118334 A118335

fini,full,nonn

Zak Seidov, Apr 23 2006

approved