OFFSET
1,3
COMMENTS
Dirichlet inverse of A206369.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
MATHEMATICA
a[1] = 1; a[n_] := -Sum[(n/d) DivisorSum[n/d, LiouvilleLambda[#]/# &] a[d], {d, Most @ Divisors[n]}]; Table[a[n], {n, 1, 70}]
Table[DivisorSum[n, MoebiusMu[n/#]^2 MoebiusMu[#] # &], {n, 1, 70}]
f[p_, e_] := If[e < 3, -p - e + 2, 0]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Dec 02 2020 *)
PROG
(PARI) a(n) = sumdiv(n, d, moebius(n/d)^2*moebius(d)*d); \\ Michel Marcus, Dec 02 2020
CROSSREFS
KEYWORD
sign,mult
AUTHOR
Ilya Gutkovskiy, Oct 26 2019
STATUS
approved