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 A316090 #16 Jun 25 2018 06:22:45
%S A316090 1,2,2,48,94,5694,12352,1539850,3323890,737028224,1556371198,
%T A316090 548747031342,1138137849328,586694732526026,1202647898994626,
%U A316090 852409708509446800,1734703213512100766,1616070775292699964094,3273912763003648926368,3875483980992048140938410
%N A316090 a(n) = [x^n] (Sum_{k=0..n} (k*x)^k)/(Sum_{k=0..n} (-k*x)^k).
%H A316090 Seiichi Manyama, <a href="/A316090/b316090.txt">Table of n, a(n) for n = 0..386</a>
%F A316090 a(n) ~ 4 * exp(-1) * n^(n-1) if n is even and a(n) ~ 2 * n^n if n is odd. - _Vaclav Kotesovec_, Jun 25 2018
%o A316090 (PARI) N=66; x='x+O('x^N); Vec((sum(k=0, N, (k*x)^k))/(sum(k=0, N, (-k*x)^k)))
%Y A316090 Cf. A000312, A296715, A303565.
%K A316090 nonn
%O A316090 0,2
%A A316090 _Seiichi Manyama_, Jun 24 2018