%I #8 Jun 13 2022 02:26:10
%S 5,19,67,107,593,757,1801,2243,2383,6043,10181,11383,15629
%N Numbers k such that (11^k - 7^k)/4 is prime.
%C All terms are prime.
%C The corresponding primes: 36061, 15286922888307293287, 1483371444025889427763765389467527889556636442659800720575790059738807, ...
%t Select[Range[1, 10000], PrimeQ[(11^# - 7^#)/4] &]
%o (PARI) for(n=1, 10000, if(isprime((11^n - 7^n)/4), print1(n, ", ")))
%Y Cf. A005808, A210506, A128027, A216181, A128347, A273598, A273600, A273601, A062577.
%K nonn,more,hard
%O 1,1
%A _Tim Johannes Ohrtmann_, May 26 2016