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 A304581 #11 Feb 16 2025 08:33:54
%S A304581 0,0,1,1,41,13,8009,161,190513,167101,13371157,21857,316786853,371449,
%T A304581 52598187029,260957190289,129548894873,3562512061,295728132584141,
%U A304581 814542451061,105590441859671453,21013691164284241,2988054680665783,5623939943287,1567371864703176307
%N A304581 Numerator of Sum_{k=1..n-1} 1/(k*(n-k))^2.
%C A304581 Sum_{k=1..n-1} 1/(k*(n-k))^2 is asymptotic to Pi^2/(3*n^2) + 4*log(n)/n^3.
%H A304581 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Dilogarithm.html">Dilogarithm</a>.
%H A304581 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Polylogarithm.html">Polylogarithm</a>.
%e A304581 0, 0, 1, 1/2, 41/144, 13/72, 8009/64800, 161/1800, 190513/2822400, ...
%t A304581 CoefficientList[Series[PolyLog[2, x]^2, {x, 0, 25}], x]//Numerator
%t A304581 Table[Sum[1/(k*(n - k))^2, {k, 1, n - 1}], {n, 0, 25}]//Numerator
%Y A304581 Cf. A002547, A304582, A302827.
%K A304581 nonn,frac
%O A304581 0,5
%A A304581 _Vaclav Kotesovec_, May 15 2018