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%I #9 Mar 16 2024 09:35:41
%S 1,1,1,2,144,72,64800,1800,2822400,3175200,317520000,635040,
%T 11064936960,15367968,2545242860160,14609174580000,8310997094400,
%U 259718659200,24319016372851200,75058692508800,10838475198270720000,2389883781218693760,374701571140216320
%N Denominator of Sum_{k=1..n-1} 1/(k*(n-k))^2.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Dilogarithm.html">Dilogarithm</a>.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Polylogarithm.html">Polylogarithm</a>.
%e 0, 0, 1, 1/2, 41/144, 13/72, 8009/64800, 161/1800, 190513/2822400, ...
%t CoefficientList[Series[PolyLog[2, x]^2, {x, 0, 25}], x]//Denominator
%t Table[Sum[1/(k*(n - k))^2, {k, 1, n - 1}], {n, 0, 25}]//Denominator
%Y Cf. A002548, A304581, A302827.
%K nonn,frac
%O 0,4
%A _Vaclav Kotesovec_, May 15 2018
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