A118332 Primes of the form n!! + (n+1)!!.

2, 3, 5, 11, 23

Offset

1,1

Comments

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

Links

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

Mathematica

Select[Array[#!! + (# + 1)!! &, 12, 0], PrimeQ]  (* James C. McMahon, Sep 24 2024 *)

Crossrefs

Cf. A118333.

Sequence in context: A073879 A073880 A376856 * A118333 A131101 A188534

Adjacent sequences: A118329 A118330 A118331 * A118333 A118334 A118335

Keyword

fini,full,nonn

Author

Zak Seidov, Apr 23 2006

Status

approved