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 A304654 #4 May 16 2018 04:05:35
%S A304654 0,0,4,27,328,6500,192216,7952112,438941952,31185057024,2772643115520,
%T A304654 301622403456000,39413353102848000,6091955683706880000,
%U A304654 1099401414283210752000,229088914497045356544000,54589580461769879715840000,14750581694440372638842880000
%N A304654 a(n) = (n!)^2 * Sum_{k=1..n-1} 1/(k^2*(n-k)).
%F A304654 Recurrence: (2*n - 3)*a(n) = (6*n^3 - 25*n^2 + 33*n - 12)*a(n-1) - (n-2)^2*(6*n^3 - 29*n^2 + 42*n - 15)*a(n-2) + (n-3)^3*(n-2)^3*(2*n - 1)*a(n-3).
%F A304654 a(n)/(n!)^2 ~ Pi^2/(6*n).
%t A304654 Table[(n!)^2 * Sum[1/(k^2*(n-k)), {k, 1, n-1}], {n, 0, 20}]
%Y A304654 Cf. A052517, A302827, A304589, A304655.
%K A304654 nonn
%O A304654 0,3
%A A304654 _Vaclav Kotesovec_, May 16 2018