1,2

If n = Product p(i)^r(i) then opsigma(n) = Product (1+(p(i)^(s(i)+2)-p(i))/(p(i)^2-1)), where si=ri when ri is odd, si=ri-1 when ri is even.

Sequence in context: A109506 A000113 A069915 this_sequence A111970 A141730 A127737

Adjacent sequences: A033631 A033632 A033633 this_sequence A033635 A033636 A033637

nonn,mult

Yasutoshi Kohmoto (zbi74583(AT)boat.zero.ad.jp)