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 A352251 #12 Mar 10 2022 08:27:11
%S A352251 1,2,28,966,62280,6452650,980531916,205438870014,56760128400016,
%T A352251 19994672935658322,8746764024725937300,4651991306703670964518,
%U A352251 2956156902003429777549144,2212026607642404922284728826,1925137044528752884360406444380,1928103808741894922401976601295950
%N A352251 Expansion of e.g.f. 1 / (1 - x * sinh(x)) (even powers only).
%F A352251 a(0) = 1; a(n) = 2 * Sum_{k=1..n} binomial(2*n,2*k) * k * a(n-k).
%t A352251 nmax = 30; Take[CoefficientList[Series[1/(1 - x Sinh[x]), {x, 0, nmax}], x] Range[0, nmax]!, {1, -1, 2}]
%t A352251 a[0] = 1; a[n_] := a[n] = 2 Sum[Binomial[2 n, 2 k] k a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 15}]
%o A352251 (PARI) my(x='x+O('x^40), v=Vec(serlaplace(1 /(1-x*sinh(x))))); vector(#v\2, k, v[2*k-1]) \\ _Michel Marcus_, Mar 10 2022
%Y A352251 Cf. A006153, A006154, A009233, A094088, A205571, A210672, A351762, A352250, A352252, A352253.
%K A352251 nonn
%O A352251 0,2
%A A352251 _Ilya Gutkovskiy_, Mar 09 2022