%I

%S 0,1,2,3,5,6,7,10,39,99,115,158,697,966,2602,2899,4057,5226

%N Numbers n such that 3*7^n + 2 is prime.

%t Do[ If[ PrimeQ[ 3*7^n + 2 ], Print[n] ], {n, 1, 6000} ]

%o (PARI) is(n)=ispseudoprime(3*7^n+2) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn

%O 1,3

%A _Robert G. Wilson v_, Feb 12 2001