OFFSET
1,3
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..10000
MATHEMATICA
a[n_] := DivisorSum[n, If[# == 1, 0, DivisorSigma[0, # - 1]] &]; Array[a, 100] (* G. C. Greubel, Dec 11 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladeta Jovovic, Aug 23 2003
STATUS
approved