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 A375561 #8 Aug 19 2024 12:14:42
%S A375561 1,0,0,6,0,60,720,1680,40320,453600,3326400,67858560,878169600,
%T A375561 11935123200,240708948480,3946374432000,73927190937600,
%U A375561 1621341859737600,32960791774310400,758085507686707200,18570669277095936000,454016684061997056000,12100759898595611443200
%N A375561 Expansion of e.g.f. 1 / (1 + x * log(1 - x^2)).
%F A375561 a(n) = n! * Sum_{k=0..floor(n/2)} (n-2*k)! * |Stirling1(k,n-2*k)|/k!.
%o A375561 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1+x*log(1-x^2))))
%o A375561 (PARI) a(n) = n!*sum(k=0, n\2, (n-2*k)!*abs(stirling(k, n-2*k, 1))/k!);
%Y A375561 Cf. A052830, A375562.
%Y A375561 Cf. A353226.
%K A375561 nonn
%O A375561 0,4
%A A375561 _Seiichi Manyama_, Aug 19 2024