1,3

Table of n, a(n) for n=1..79.

G.f.: Sum_{k>0} x^k/(1-x^(2k))^2 = Sum_{k>0} k x^(2k-1)/(1-x^(2k-1)).

(PARI) a(n)=if(n<1, 0, sumdiv(n, d, if(d%2, (d+1)/2)))

Sequence in context: A082909 A029151 A102595 * A054019 A230877 A209613

Adjacent sequences: A113412 A113413 A113414 * A113416 A113417 A113418

nonn

Michael Somos, Oct 29 2005

approved