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 A375627 #8 Aug 22 2024 09:17:18
%S A375627 1,1,6,24,168,1260,11760,126000,1545600,21304080,326350080,5497873920,
%T A375627 101048048640,2011924474560,43139969832960,991088998099200,
%U A375627 24286975237324800,632358338278867200,17433184834127462400,507307459608530380800,15539683835941532467200
%N A375627 Expansion of e.g.f. exp(2*x^2) / (1 - x * exp(x^2)).
%F A375627 a(n) = n! * Sum_{k=0..floor(n/2)} (n-2*k+2)^k/k!.
%o A375627 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(2*x^2)/(1-x*exp(x^2))))
%o A375627 (PARI) a(n) = n!*sum(k=0, n\2, (n-2*k+2)^k/k!);
%Y A375627 Cf. A368265, A375628.
%Y A375627 Cf. A358064, A375604.
%K A375627 nonn
%O A375627 0,3
%A A375627 _Seiichi Manyama_, Aug 21 2024