%I #17 Apr 01 2023 14:50:23

%S 1,17,1295

%N Numbers k such that 1 + 2^k + 3^k + 5^k is prime.

%C a(4), if it exists, is greater than 50000. - _Michael S. Branicky_, Mar 31 2023

%t Select[Range[0, 2000], PrimeQ[1 + 2^# + 3^# + 5^#] &]

%o (PARI) lista(nn) = for(n=0, nn, if(ispseudoprime(1 + 2^n + 3^n + 5^n), print1(n, ", "))); \\ _Altug Alkan_, Jan 25 2016

%Y Cf. A076515, A268064, A268065.

%K nonn,bref,more

%O 1,2

%A _Vaclav Kotesovec_, Jan 25 2016