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 A362321 #14 Feb 16 2025 08:34:05
%S A362321 1,1,1,1,97,601,2161,5881,1303681,14723857,90770401,402581521,
%T A362321 139389608161,2284512533161,19946635524817,122623661651401,
%U A362321 57728368477678081,1240234284406887841,14010634784751445441,110117252571345122977
%N A362321 a(n) = n! * Sum_{k=0..floor(n/4)} n^k /(k! * (n-4*k)!).
%H A362321 Winston de Greef, <a href="/A362321/b362321.txt">Table of n, a(n) for n = 0..408</a>
%H A362321 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LambertW-Function.html">Lambert W-Function</a>.
%F A362321 a(n) = n! * [x^n] exp(x + n*x^4).
%F A362321 E.g.f.: exp( ( -LambertW(-4*x^4)/4 )^(1/4) ) / (1 + LambertW(-4*x^4)).
%o A362321 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(exp((-lambertw(-4*x^4)/4)^(1/4))/(1+lambertw(-4*x^4))))
%Y A362321 Cf. A362301, A362323.
%K A362321 nonn
%O A362321 0,5
%A A362321 _Seiichi Manyama_, Apr 16 2023