OFFSET
1,2
MATHEMATICA
Table[DivisorSum[n, MoebiusMu[n/#]*#^n/EulerPhi[n]&], {n, 20}] (* Giorgos Kalogeropoulos, May 13 2021 *)
PROG
(PARI) a(n) = sumdiv(n, d, moebius(n/d)*d^n)/eulerphi(n);
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, May 12 2021
STATUS
approved