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 A375662 #12 Sep 01 2024 09:35:43
%S A375662 1,0,0,12,24,40,2220,15204,70672,1723824,22710420,202577980,
%T A375662 3841065624,71221859592,994632663388,19005155049300,421055077585440,
%U A375662 8033764197776224,172109549363348772,4285658639255113836,101794836650015825320,2516190299149752959160
%N A375662 Expansion of e.g.f. 1 / (1 - x^2 * (exp(x) - 1))^2.
%F A375662 E.g.f.: B(x)^2, where B(x) is the e.g.f. of A358013.
%F A375662 a(n) = n! * Sum_{k=0..floor(n/3)} (k+1)! * Stirling2(n-2*k,k)/(n-2*k)!.
%o A375662 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1-x^2*(exp(x)-1))^2))
%o A375662 (PARI) a(n) = n!*sum(k=0, n\3, (k+1)!*stirling(n-2*k, k, 2)/(n-2*k)!);
%Y A375662 Cf. A358013, A375663.
%K A375662 nonn
%O A375662 0,4
%A A375662 _Seiichi Manyama_, Aug 23 2024