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 A277480 #14 Nov 06 2017 02:42:31
%S A277480 0,0,2,6,28,280,3486,50624,877080,17677440,404537050,10360548352,
%T A277480 293676213876,9126971869184,308568877413174,11274243944693760,
%U A277480 442681525701106096,18588860836606935040,831243363178769061426,39436124829328468606976,1978382154057910059275340
%N A277480 E.g.f.: -tanh(x)*LambertW(-x).
%H A277480 Robert Israel, <a href="/A277480/b277480.txt">Table of n, a(n) for n = 0..387</a>
%F A277480 a(n) ~ tanh(exp(-1)) * n^(n-1).
%F A277480 a(n) = Sum_{k=0..floor(n/2)-1} binomial(n,2*k+1)*(m-2*k-1)^(m-2*k-2) - Sum_{k=1..floor(n/2)} binomial(n,2*k)*a(n-2*k). - _Robert Israel_, Oct 26 2016
%p A277480 F:= proc(m) option remember; add(binomial(m,2*k+1)*(m-2*k-1)^(m-2*k-2),k=0..floor(m/2)-1) - add(binomial(m,2*k)*procname(m-2*k),k=1..floor(m/2)) end proc:
%p A277480 map(F, [$0..30]); # _Robert Israel_, Oct 26 2016
%t A277480 CoefficientList[Series[-Tanh[x]*LambertW[-x], {x, 0, 20}], x] * Range[0, 20]!
%o A277480 (PARI) x='x+O('x^50); concat([0,0],Vec(serlaplace(tanh(-x)*lambertw(-x))) ) \\ _G. C. Greubel_, Nov 05 2017
%Y A277480 Cf. A000169, A277468, A277473, A277479.
%K A277480 nonn
%O A277480 0,3
%A A277480 _Vaclav Kotesovec_, Oct 17 2016