%I
%S 1,2,3,4,5,6,7,11,13,14,15,16,17,19,21,22,24,25,26,30,32,35,36,38,43,
%T 44,49,52,54,55,60,61,62,63,66,69,70,71,73,74,79,80,81,82,85,87,88,93,
%U 94,101,104,106,107,109,110,112,114,115,117,123,127,128,131,135
%N Numbers k such that 5*k^2 + 5*k + 1 is prime.
%t Do[s=5*n^2+5*n+1; If[PrimeQ[s], Print[n]], {n, 1, 1000}]
%o (PARI) isok(n) = isprime(5*n^2+5*n+1); \\ _Michel Marcus_, Apr 30 2016
%Y Cf. A090562.
%K nonn
%O 1,2
%A _Amarnath Murthy_, Dec 11 2003
%E More terms from _Labos Elemer_, Dec 12 2003
%E Offset corrected by _Arkadiusz Wesolowski_, Aug 09 2011
