A171058 - OEIS

%I #20 Jul 25 2024 07:42:04

%S 0,1,3,41,45,83,95,181,193,195,311,325,901,1825,3649,7709,16335,45547

%N Numbers k such that 3^k + 3*k + 1 is prime.

%C a(19) > 10^5. - _Michael S. Branicky_, Jul 25 2024

%o (PARI) is(n)=ispseudoprime(3^n+3*n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%Y Numbers k such that b^k + b*k + 1 is prime: A301634 (b=2), this sequence (b=3), A301635 (b=5).

%Y Cf. A176805, A180269.

%K nonn,more

%O 1,3

%A _N. J. A. Sloane_, Sep 04 2010, based on a posting to the Sequence Fans Mailing List by _Charles R Greathouse IV_, Aug 23 2010

%E More terms from _Charles R Greathouse IV_, Sep 07 2010