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 A357966 #14 Oct 22 2022 14:02:14
%S A357966 1,0,0,6,0,60,360,840,20160,75600,1058400,10311840,79833600,
%T A357966 1305944640,11018367360,174616041600,2150397849600,28661419987200,
%U A357966 473667677683200,6293779652160000,114484773731328000,1766543101087564800,31640707215390873600
%N A357966 Expansion of e.g.f. exp( x * (exp(x^2) - 1) ).
%F A357966 a(n) = n! * Sum_{k=0..floor(n/2)} Stirling2(k,n-2*k)/k!.
%o A357966 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x*(exp(x^2)-1))))
%o A357966 (PARI) a(n) = n!*sum(k=0, n\2, stirling(k, n-2*k, 2)/k!);
%Y A357966 Cf. A357967, A357968.
%Y A357966 Cf. A353226.
%K A357966 nonn
%O A357966 0,4
%A A357966 _Seiichi Manyama_, Oct 22 2022