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 A375587 #9 Aug 20 2024 09:14:09
%S A375587 1,0,0,0,4,0,0,70,1120,0,2800,184800,2217600,200200,39239200,
%T A375587 1513512000,16166550400,11435424000,1029188160000,31290941281600,
%U A375587 317363510464000,821292151680000,52198475641312000,1387554839326656000,14092570281613824000,92349968764253200000
%N A375587 Expansion of e.g.f. 1 / (1 + x - x * exp(x^3/6)).
%F A375587 a(n) = n! * Sum_{k=0..floor(n/3)} (n-3*k)! * Stirling2(k,n-3*k)/(6^k*k!).
%o A375587 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1+x-x*exp(x^3/6))))
%o A375587 (PARI) a(n) = n!*sum(k=0, n\3, (n-3*k)!*stirling(k, n-3*k, 2)/(6^k*k!));
%Y A375587 Cf. A052848, A375586.
%Y A375587 Cf. A375556.
%K A375587 nonn
%O A375587 0,5
%A A375587 _Seiichi Manyama_, Aug 19 2024