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 A303566 #9 Apr 26 2018 19:00:41
%S A303566 1,4,8,40,128,1168,4448,66400,268544,6124480,25118336,827294848,
%T A303566 3386501120,153439657216,624706655744,37378784384512,151446759993344,
%U A303566 11573673369828352,46729404312578048,4439994292732364800,17884613664930529280,2067374053521268559872
%N A303566 a(n) = [x^n] (Sum_{k=0..n} (k+1)!*x^k)/(Sum_{k=0..n} (k+1)!*(-x)^k).
%H A303566 Seiichi Manyama, <a href="/A303566/b303566.txt">Table of n, a(n) for n = 0..448</a>
%o A303566 (PARI) N=66; x='x+O('x^N); Vec(sum(k=0, N, (k+1)!*x^k)/sum(k=0, N, (k+1)!*(-x)^k))
%Y A303566 Cf. A303565, A303567.
%K A303566 nonn
%O A303566 0,2
%A A303566 _Seiichi Manyama_, Apr 26 2018