A056800 Numbers n such that 6*9^n +1 is prime.

0, 2, 4, 8, 28, 32, 448, 2108, 3112, 76264

Offset: 1

Author

Robert G. Wilson v, Aug 22 2000

Keywords

• nonn

Comments

a(11) > 10^5. - Robert Price, Jun 04 2015

Programs

Mathematica

Do[If[PrimeQ[6*9^n + 1], Print[n]], {n, 0, 1000}]
Select[Range[3000], PrimeQ[6 9^# + 1] &] (* Vincenzo Librandi, Sep 28 2012 *)

PARI

is(n)=ispseudoprime(6*9^n+1) \\ Charles R Greathouse IV, Jun 12 2017

Extensions

a(8) from Vincenzo Librandi, Sep 28 2012

a(9)-a(10) from Robert Price, Jun 04 2015