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 A302586 #7 Jun 08 2019 08:32:53
%S A302586 0,1,4,29,288,3641,55872,1008349,20923392,490730641,12836633600,
%T A302586 370512824285,11697136754688,400947361714121,14829211483455488,
%U A302586 588633245015433437,24960134277040177152,1126038686507284428961,53851620649898789830656,2721385807644104827095965
%N A302586 a(n) = n! * [x^n] exp(n*x)*tan(x).
%H A302586 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>
%F A302586 a(n) ~ tan(1) * n^n. - _Vaclav Kotesovec_, Jun 08 2019
%t A302586 Table[n! SeriesCoefficient[Exp[n x] Tan[x], {x, 0, n}], {n, 0, 19}]
%t A302586 Table[I^(n + 1) 2^(n - 1) (EulerE[n, (-I/2) n] - EulerE[n, 1 - (I/2) n]), {n, 0, 19}]
%Y A302586 Cf. A000182, A009739, A115415, A115416, A293020, A302583, A302584, A302585, A302587.
%K A302586 nonn
%O A302586 0,3
%A A302586 _Ilya Gutkovskiy_, Apr 10 2018