This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A218373 #8 Jun 13 2017 14:26:02
%S A218373 3,5,19,41,47,8231,33931,43781,50833,53719,67211
%N A218373 Numbers n such that (7^n + 4^n)/11 is prime.
%C A218373 All terms are primes.
%C A218373 a(11) > 10^5
%t A218373 Do[ p=Prime[n]; f=(7^p+4^p)/11; If[ PrimeQ[f], Print[p]], {n, 1, 9592} ]
%o A218373 (PARI) is(n)=ispseudoprime((7^n+4^n)/11) \\ _Charles R Greathouse IV_, Jun 13 2017
%Y A218373 Cf. A128335, A128067, A128337.
%K A218373 hard,more,nonn
%O A218373 1,1
%A A218373 _Robert Price_, Oct 27 2012