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 A216420 #26 Sep 08 2022 08:46:03 %S A216420 1,5,85,155,383,6223 %N A216420 Numbers k such that 13^k + k^13 - 1 is prime. %C A216420 a(7) > 2*10^5 if it exists. - _Robert Price_, Jul 07 2014 %t A216420 Select[Range[0, 5000], PrimeQ[13^# + #^13 - 1] &] %o A216420 (Magma) [n: n in [0..1000] | IsPrime(13^n+n^13-1)]; %o A216420 (PARI) is(n)=ispseudoprime(13^n+n^13-1) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A216420 Cf. A100357, A215434-A215437, A215439-A215445, A216375. %K A216420 nonn,hard,more %O A216420 1,2 %A A216420 _Vincenzo Librandi_, Sep 07 2012 %E A216420 a(6) from _Robert Price_, May 24 2014