A177093 Numbers n such that 9^n-8 is prime.

2, 4, 7, 10, 11, 31, 127, 136, 215, 953, 1139, 1799, 3406, 7633, 13090, 13171, 13511, 32593

Offset: 1

Author

Vincenzo Librandi, Nov 15 2010

Keywords

• nonn
• more

Comments

a(19) > 2*10^5. - Robert Price, Jul 29 2015

Crossrefs

Cf. A177094.

Programs

Magma

[n: n in [1..900]| IsPrime(9^n-8)]

Maple

A177093:=n->`if`(isprime(9^n-8), n, NULL): seq(A177093(n), n=1..10^3); # Wesley Ivan Hurt, Nov 14 2014

Mathematica

Select[Range[1000], PrimeQ[9^#-8] &] (* Vincenzo Librandi, Nov 15 2014 *)

PARI

is(n)=isprime(9^n-8) \\ Charles R Greathouse IV, Nov 15 2014

Extensions

Extended and crossref added by D. S. McNeil, Nov 15 2010

a(14)-a(18) from Robert Price, Jul 29 2015