%I

%S 2,3,4,5,6,10,11,41,83,160,178,526,881,2578,3772

%N n such that 3^(2n-3)+3^(n-1)+1 is prime.

%C n such that A198410(n) is prime.

%t Select[Range[250], PrimeQ[((3^(#-1) + 1)^3 -1)/3^#]&]

%Y Cf. A198410, A199192.

%K nonn,hard

%O 1,1

%A _Michel Lagneau_, Nov 03 2011