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 A334735 #11 May 09 2020 15:29:18
%S A334735 1,4,18,96,2880,518400,181440,135475200,8778792960,376233984000,
%T A334735 72425041920000,4588850656051200,47345284546560000,
%U A334735 217144413044342784000,42750306318104985600000,4974581098834034688000000,70875936417673484697600000,13663463022599094380003328000000
%N A334735 Denominator of Sum_{k=1..n} k^2 / Product_{k=1..n} k^2.
%F A334735 a(n) = denominator(n*(n + 1)*(2*n + 1)/6/(n!)^2).
%e A334735 The first few fractions are 1, 5/4, 7/18, 5/96, 11/2880, 91/518400, 1/181440, 17/135475200, 19/8778792960, ... = A125294/A334735.
%t A334735 Table[Denominator[n*(n + 1)*(2*n + 1)/(6*(n!)^2)], {n, 1, 18}] (* _Amiram Eldar_, May 09 2020 *)
%o A334735 (PARI) a(n) = denominator(sum(k=1, n, k^2)/prod(k=1, n, k^2)); \\ _Michel Marcus_, May 09 2020
%Y A334735 Cf. A125294 (numerators), A166602.
%K A334735 nonn,frac
%O A334735 1,2
%A A334735 _Petros Hadjicostas_, May 09 2020