Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #30 Sep 08 2022 08:45:53
%S 2,4,7,10,11,31,127,136,215,953,1139,1799,3406,7633,13090,13171,13511,
%T 32593
%N Numbers n such that 9^n-8 is prime.
%C a(19) > 2*10^5. - _Robert Price_, Jul 29 2015
%p A177093:=n->`if`(isprime(9^n-8), n, NULL): seq(A177093(n), n=1..10^3); # _Wesley Ivan Hurt_, Nov 14 2014
%t Select[Range[1000], PrimeQ[9^#-8] &] (* _Vincenzo Librandi_, Nov 15 2014 *)
%o (Magma) [n: n in [1..900]| IsPrime(9^n-8)]
%o (PARI) is(n)=isprime(9^n-8) \\ _Charles R Greathouse IV_, Nov 15 2014
%Y Cf. A177094.
%K nonn,more
%O 1,1
%A _Vincenzo Librandi_, Nov 15 2010
%E Extended and crossref added by _D. S. McNeil_, Nov 15 2010
%E a(14)-a(18) from _Robert Price_, Jul 29 2015