A056799 Numbers n such that 8*9^n +1 is prime.

1, 4, 5, 11, 26, 29, 38, 65, 166, 490, 641, 2300, 9440, 44741, 65296, 161930, 586240

Offset

1,2

Comments

The even members of A005538, halved. - Jeppe Stig Nielsen, Oct 13 2019

Links

Table of n, a(n) for n=1..17.

Mathematica

Do[If[PrimeQ[8*9^n + 1], Print[n]], {n, 0, 1000}]
Select[Range[3000], PrimeQ[8 9^# + 1] &] (* Vincenzo Librandi, Sep 28 2012 *)

Prog

(PARI) is(n)=ispseudoprime(8*9^n+1) \\ Charles R Greathouse IV, Mar 01 2017

Crossrefs

Cf. A005538.

Sequence in context: A000769 A246495 A050831 * A216963 A259821 A352681

Adjacent sequences: A056796 A056797 A056798 * A056800 A056801 A056802

Keyword

nonn,more

Author

Robert G. Wilson v, Aug 22 2000

Extensions

a(12) from Vincenzo Librandi, Sep 28 2012

a(13)-a(16) from Robert Price, Feb 22 2016

a(17) from Paul S. Vanderveen, Jul 04 2020

Status

approved