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 A175878 #2 Mar 30 2012 17:26:35
%S A175878 3,7,15,564210119465811
%N A175878 Odd terms in A007497.
%t A175878 n=2;Do[If[OddQ[n=DivisorSigma[1,n]],Print[n]],{k,2,99}]
%Y A175878 A007497, A175877.
%K A175878 more,nonn
%O A175878 1,1
%A A175878 _Zak Seidov_, Oct 07 2010