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 A355181 #15 Feb 16 2025 08:34:03
%S A355181 0,0,0,3,6,10,195,1281,5908,90756,1098765,9605035,147947646,
%T A355181 2496239538,33836915203,588360763095,12104789358600,223722576473896,
%U A355181 4578806487368313,108875473376842467,2519418390663035170,60831875074927797750,1640260621340460494991
%N A355181 Expansion of e.g.f. -LambertW(x^2/2 * (1 - exp(x))).
%H A355181 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LambertW-Function.html">Lambert W-Function</a>.
%F A355181 a(n) = n! * Sum_{k=1..floor(n/3)} k^(k-1) * Stirling2(n-2*k,k)/(2^k * (n-2*k)!).
%o A355181 (PARI) my(N=30, x='x+O('x^N)); concat([0, 0, 0], Vec(serlaplace(-lambertw(x^2/2*(1-exp(x))))))
%o A355181 (PARI) a(n) = n!*sum(k=1, n\3, k^(k-1)*stirling(n-2*k, k, 2)/(2^k*(n-2*k)!));
%Y A355181 Cf. A048802, A355308, A357267.
%K A355181 nonn
%O A355181 0,4
%A A355181 _Seiichi Manyama_, Sep 24 2022