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 A216181 #14 Feb 20 2017 14:46:16 %S A216181 3,5,11,17,71,89,827,22307,45893,63521 %N A216181 Numbers n such that (11^n - 4^n)/7 is prime. %C A216181 All terms are prime. %C A216181 Next term > 10^5. %t A216181 Select[Prime[Range[1, 100000]], PrimeQ[(11^# - 4^#)/7]&] %o A216181 (PARI) is(n)=ispseudoprime((11^n-4^n)/7) \\ _Charles R Greathouse IV_, Feb 20 2017 %Y A216181 Cf. A004063, A028491, A057468, A059801, A121877, A128024, A128025, A128026, A128027, A128028, A128029, A128030, A128031, A128032, A210506. %K A216181 nonn,hard,more %O A216181 1,1 %A A216181 _Robert Price_, Mar 11 2013