2,4

A dual sequence to A243154. The sequence contains a unique zero term. Indeed, every prime p>3 has the form 3*k +/- 1. So, p^2 + 2 == 0 (mod 3).

Table of n, a(n) for n=2..82.

(PARI) vector(200, n, k=0; while(!isprime(prime(n+1)*prime(n+1+k)+2), k++); k) \\ Colin Barker, May 31 2014

Cf. A243154.

Sequence in context: A016475 A037227 A056753 * A154723 A273262 A274532

Adjacent sequences: A243155 A243156 A243157 * A243159 A243160 A243161

nonn

Vladimir Shevelev, May 31 2014

More terms from Colin Barker, May 31 2014

approved