login
Numbers n such that 8^n - 5 is prime.
2

%I #20 Jun 06 2017 14:32:55

%S 1,2,4,6,12,22,50,270,606,800,1704,5462,6194,9206,10306,105380

%N Numbers n such that 8^n - 5 is prime.

%C All terms are equal to 1/3 of the multiples of 3 in A059608.

%t Select[Range[4000], PrimeQ[8^# - 5] &]

%o (PARI) is(n)=ispseudoprime(8^n-5) \\ _Charles R Greathouse IV_, Jun 06 2017

%Y Cf. A059608, A217355.

%K nonn

%O 1,2

%A _Vincenzo Librandi_, Oct 02 2012