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 A365980 #11 Sep 24 2023 09:16:34
%S A365980 1,0,0,2,0,24,80,720,5376,53760,490752,6289920,68766720,1024607232,
%T A365980 13520332800,226177695744,3498759290880,65257155624960,
%U A365980 1153246338220032,23793010526453760,472374431008948224,10686755493583257600,235406405307208826880
%N A365980 Expansion of e.g.f. 1 / ( 1 - Sum_{k>=0} x^(2*k+3) / (2*k+3) ).
%F A365980 a(0) = 1; a(n) = Sum_{k=0..floor((n-3)/2)} (2*k+2)! * binomial(n,2*k+3) * a(n-2*k-3).
%F A365980 E.g.f.: 1 / ( 1 + x - arctanh(x) ).
%o A365980 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1+x-atanh(x))))
%Y A365980 Cf. A355284, A365981, A365982.
%Y A365980 Cf. A130915, A296676.
%K A365980 nonn
%O A365980 0,4
%A A365980 _Seiichi Manyama_, Sep 23 2023