OFFSET
1,4
LINKS
MATHEMATICA
f[p_, e_] := NextPrime[p]^e; s[1] = 1; s[n_] := (1 + Times @@ f @@@ FactorInteger[n])/2; a[n_] := DivisorSum[n, s[#] &, # < n &]; Array[a, 100] (* Amiram Eldar, Dec 12 2021 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Dec 10 2021
STATUS
approved