OFFSET
1,4
COMMENTS
Inverse Möbius transform of A003415.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
MATHEMATICA
Block[{a}, a[1] = 0; a[n_] := a[n] = If[n < 2, 0, n Total[#2/#1 & @@@ FactorInteger[n]]]; Array[DivisorSum[#, a[#] &] &, 91]] (* Michael De Vlieger, May 24 2021 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Oct 02 2018
STATUS
approved