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 A096950 #10 Sep 01 2013 02:23:11 %S A096950 1,27,405,25515,2066715,7577955,2659862205,71816279535,3662630256285, %T A096950 626309773824735,2415766270466835,166687872662211615, %U A096950 7500954269799522675,1822731887561284010025,52859224739277236290725 %N A096950 Denominators of partial sums of series for 3*arctanh(1/3) = (3/2)*log(2). %C A096950 Numerators are given in A096949. %F A096950 a(n)=denominator(A(n)) with the rational number A(n):= sum(((1/3)^(2*k))/(2*k+1), k=0..n) in lowest terms. %e A096950 n=10: A096949(10)/2415766270466835 = 2511722368895123/2415766270466835 = 1.039720770838... approximates 3*arctanh(1/3)= 1.039720770840... %K A096950 nonn,easy,frac %O A096950 0,2 %A A096950 _Wolfdieter Lang_, Jul 16 2004