%I #2 Mar 30 2012 17:26:35
%S 2,4,6,33
%N Positions of odd terms in A007497.
%C Corresponding odd terms 3,7,15,564210119465811 (A175878).
%t n=2;Do[If[OddQ[n=DivisorSigma[1,n]],Print[{k,n}]],{k,2,99}]
%Y A007497, A175878.
%K more,nonn
%O 1,1
%A _Zak Seidov_, Oct 07 2010