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 A365973 #9 Sep 24 2023 09:16:09
%S A365973 1,0,0,2,0,0,40,720,0,2240,172800,3628800,246400,49420800,3531340800,
%T A365973 87223136000,18450432000,3006222336000,225434879488000,
%U A365973 6411312940032000,2744461025280000,435228787435520000,35074217524469760000,1126838040745697280000
%N A365973 Expansion of e.g.f. exp( Sum_{k>=0} x^(4*k+3) / (4*k+3) ).
%F A365973 a(0) = 1; a(n) = (n-1)! * Sum_{k=0..floor((n-3)/4)} a(n-4*k-3)/(n-4*k-3)!.
%o A365973 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(sum(k=0, N\4, x^(4*k+3)/(4*k+3)))))
%Y A365973 Cf. A038205, A130915, A365974.
%Y A365973 Cf. A365981.
%K A365973 nonn
%O A365973 0,4
%A A365973 _Seiichi Manyama_, Sep 23 2023