1,2

These are the indices of the primes in A082040.

Table of n, a(n) for n=1..60.

select(n->isprime(9*n^2+3*n+1), [$0..300]);

(GAP) Filtered([0..300], n->IsPrime(9*n^2+3*n+1));

Cf. A082040, A303740 (corresponding primes).

Sequence in context: A187351 A026451 A050106 * A183544 A219640 A184164

Adjacent sequences: A303736 A303737 A303738 * A303740 A303741 A303742

nonn

Muniru A Asiru, Jun 01 2018

approved