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 A130414 #13 Jul 27 2015 22:05:52 %S A130414 1,18,45,1260,945,20790,135135,1081080,765765,87297210,43648605, %T A130414 4015671660,5019589575,30117537450,436704293025,216605329340400, %U A130414 13537833083775,27075666167550,500899824099675,2003599296398700 %N A130414 Denominators of partial sums for a series for Pi/3. %C A130414 The numerators are given in A130413. %C A130414 For the rationals r(n) see A130413 and the W. Lang link given there. %H A130414 Robert Israel, <a href="/A130414/b130414.txt">Table of n, a(n) for n = 0..1000</a> %F A130414 a(n) = denominator(r(n)), n>=0, with the rationals defined in A130413. %p A130414 f:= n -> denom(1+ (4/3)*add(((-1)^(j+1))/((2*j+1)*((2*j+1)^2-1)), j=1..n)): %p A130414 map(f, [$0..20]);# _Robert Israel_, Jul 27 2015 %K A130414 nonn,frac,easy %O A130414 0,2 %A A130414 _Wolfdieter Lang_, Jun 01 2007