1,2

Table of n, a(n) for n=1..64.

Do[s=5*n^2+5*n+1; If[PrimeQ[s], Print[n]], {n, 1, 1000}]

(PARI) isok(n) = isprime(5*n^2+5*n+1); \\ Michel Marcus, Apr 30 2016

Cf. A090562.

Sequence in context: A174219 A115037 A280536 * A045745 A054010 A051948

Adjacent sequences: A090560 A090561 A090562 * A090564 A090565 A090566

nonn

Amarnath Murthy, Dec 11 2003

More terms from Labos Elemer, Dec 12 2003

Offset corrected by Arkadiusz Wesolowski, Aug 09 2011

approved