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 A216421 #17 Jul 12 2018 11:28:54 %S A216421 0,9,4371,7985,14711 %N A216421 Numbers k such that 13^k + k^13 + 1 is prime. %C A216421 a(6) > 10^5. - _Robert Price_, Feb 23 2014 %t A216421 Select[Range[0, 5000], PrimeQ[13^# + #^13 + 1] &] %o A216421 (PARI) is(n)=ispseudoprime(13^n+n^13+1) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A216421 Cf. A100357, A215434-A215446, A216375. %K A216421 nonn,hard,more %O A216421 1,2 %A A216421 _Vincenzo Librandi_, Sep 07 2012 %E A216421 a(4)-a(5) from _Robert Price_, Feb 23 2014