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 A009530 #16 Apr 02 2017 03:19:46
%S A009530 1,0,12,-336,-2096,-1043328,-29488704,-8894706432,-389860902656,
%T A009530 -170568226222080,-6327905330549760,-6080018829202427904,
%U A009530 242897035394043301888,-323994054628796940582912,123697309877515731773669376,-13142696592417683099946516480
%N A009530 Expansion of e.g.f. sin(tanh(x)/cos(x)).
%C A009530 Among solutions to a(n)=2n are primes, twice primes (A001747) and also further numbers.
%t A009530 Sin[ Tanh[ x ]/Cos[ x ] ] (* Odd Part *)
%o A009530 (PARI) x='x+O('x^34); v = Vec(serlaplace(sin(tanh(x)/cos(x)))); vector(#v\2, n, v[2*n-1]) \\ _Michel Marcus_, Apr 02 2017
%K A009530 sign
%O A009530 0,3
%A A009530 _R. H. Hardin_
%E A009530 Extended with signs by _Olivier Gérard_, Mar 15 1997