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 A357591 #15 Oct 05 2022 10:09:18
%S A357591 0,0,1,3,8,25,99,476,2643,16575,116002,895719,7554311,69051034,
%T A357591 679913073,7174562327,80765185416,966076987581,12235992073975,
%U A357591 163590477924708,2302288709067167,34021599945907915,526690307104399482,8524372522971447683,143963947160570293851
%N A357591 Expansion of e.g.f. (exp(x) - 1) * tan((exp(x) - 1)/2).
%F A357591 a(n) = 2 * Sum_{k=0..floor(n/2)} (-1)^k * Stirling2(n,2*k) * (1 - 4^k) * Bernoulli(2*k).
%F A357591 a(n) ~ n! * 2*Pi / ((Pi+1) * (log(1+Pi))^(n+1)).
%t A357591 nmax = 20; CoefficientList[Series[(Exp[x] - 1)*Tan[(Exp[x] - 1)/2] , {x, 0, nmax}], x] * Range[0, nmax]!
%t A357591 Table[2*Sum[(-1)^k * StirlingS2[n, 2*k] * (1 - 4^k) * BernoulliB[2*k], {k, 0, n/2}], {n, 0, 20}]
%o A357591 (PARI) my(N=30, x='x+O('x^N)); concat([0, 0], Vec(serlaplace((exp(x)-1)*tan((exp(x)-1)/2)))) \\ _Seiichi Manyama_, Oct 05 2022
%Y A357591 Cf. A001469, A136128, A357240.
%K A357591 nonn
%O A357591 0,4
%A A357591 _Vaclav Kotesovec_, Oct 05 2022