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 A097328 #3 Mar 30 2012 17:22:33
%S A097328 1,5,45,585,9945,69615,348075,10094175,111035925,4108329225,
%T A097328 168441498225,56147166075,393030162525,20830598613825,395781373662675,
%U A097328 24142663793423175,24142663793423175,555281267248733025
%N A097328 Denominator of 1 + 1/5 + 1/9 +...+ 1/(4n+1).
%C A097328 The first 11 terms are the same as the least common multiples in A051539.
%t A097328 Table[Denominator[Total[1/Range[1, 4n+1, 4]]], {n, 0, 20}]
%Y A097328 Cf. A016813 (4n+1), A075136 (numerators), A051539 (lcm of 5, 9, 13, ..., 4n+1).
%K A097328 easy,frac,nonn
%O A097328 0,2
%A A097328 _T. D. Noe_, Aug 04 2004