OFFSET
0,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
FORMULA
G.f.: sum(n>=1, n*(n+1) * x^n/(1-x^n) )
MATHEMATICA
Join[{1}, DivisorSigma[1, #]+DivisorSigma[2, #]&/@Range[50]] (* Harvey P. Dale, Aug 12 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 20 2004
STATUS
approved