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 A362337 #17 Feb 16 2025 08:34:05
%S A362337 1,1,-1,-5,37,221,-2549,-21041,342665,3604537,-75816809,-970017949,
%T A362337 25012223149,377031935125,-11513789879773,-199833956857289,
%U A362337 7052339905578001,138505710577529969,-5546345926322582225,-121599560980889072693,5447342134797972438581
%N A362337 a(n) = n! * Sum_{k=0..floor(n/2)} (-k)^k / (k! * (n-2*k)!).
%H A362337 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/LambertW-Function.html">Lambert W-Function</a>.
%F A362337 E.g.f.: exp(x) / (1 + LambertW(x^2)).
%o A362337 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(x)/(1+lambertw(x^2))))
%Y A362337 Cf. A069856, A362338, A362339.
%Y A362337 Cf. A362347.
%K A362337 sign
%O A362337 0,4
%A A362337 _Seiichi Manyama_, Apr 17 2023