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 A362859 #14 Feb 16 2025 08:34:05
%S A362859 1,1,13,173,3321,81529,2443333,86475493,3529941873,163260749681,
%T A362859 8437633695741,481912844592541,30142773978386281,2049173019206244073,
%U A362859 150443505029536707381,11862692305729094644949,999864950902004743707873,89709634016056661732903137
%N A362859 Expansion of e.g.f. exp(-x) / (1 + LambertW(-2*x)).
%H A362859 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LambertW-Function.html">Lambert W-Function</a>.
%F A362859 G.f.: Sum_{k>=0} (2*k*x)^k / (1 + x)^(k+1).
%F A362859 a(n) = (-1)^n * Sum_{k=0..n} (-2*k)^k * binomial(n,k).
%o A362859 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(-x)/(1 + lambertw(-2*x))))
%Y A362859 Column k=2 of A362019.
%Y A362859 Cf. A062971, A362857.
%K A362859 nonn,easy
%O A362859 0,3
%A A362859 _Seiichi Manyama_, May 05 2023