OFFSET
1,4
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..20000
MATHEMATICA
nusigma[1] = 0; nusigma[n_] := DivisorSigma[1, n] - Times @@ (1 + Power @@@ FactorInteger[n]); a[n_] := DivisorSum[n, MoebiusMu[n/#]*nusigma[#] &]; Array[a, 100] (* Amiram Eldar, Oct 30 2021 *)
PROG
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Oct 29 2021
STATUS
approved