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 A302608 #15 Oct 25 2024 10:14:57
%S A302608 0,1,4,25,224,2649,38880,679449,13749248,315919665,8122432000,
%T A302608 231002307449,7199799644160,244028744225993,8936047251296256,
%U A302608 351569799174274425,14789182545666244608,662389019735008588129,31470659616611382460416,1580849762199983023572313
%N A302608 a(n) = n! * [x^n] exp(n*x)*arctan(x).
%H A302608 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>
%F A302608 a(n) ~ arctan(1) * n^n. - _Vaclav Kotesovec_, Jun 09 2019
%F A302608 a(n) = Sum_{k=1..n, k odd} (-1)^((k-1)/2)*binomial(n,k)*(k-1)!*n^(n-k). - _Fabian Pereyra_, Oct 05 2024
%t A302608 Table[n! SeriesCoefficient[Exp[n x] ArcTan[x], {x, 0, n}], {n, 0, 19}]
%t A302608 Join[{0}, Table[n^n (HypergeometricPFQ[{1, 1, 1 - n}, {2}, -(I/n)] + HypergeometricPFQ[{1, 1, 1 - n}, {2}, I/n])/2, {n, 19}]]
%Y A302608 Cf. A010050, A279927, A293192, A302583, A302584, A302585, A302586, A302587, A302605, A302606, A302609.
%K A302608 nonn
%O A302608 0,3
%A A302608 _Ilya Gutkovskiy_, Apr 10 2018