OFFSET
1,8
COMMENTS
Inverse Moebius transform applied twice to A076479 (unitary Moebius function).
LINKS
FORMULA
MATHEMATICA
Table[Sum[(-1)^PrimeNu[n/d] DivisorSigma[0, d], {d, Divisors[n]}], {n, 1, 85}]
f[p_, e_] := (e + 1)*(2 - e)/2; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Oct 26 2020 *)
PROG
(PARI) A326815(n) = sumdiv(n, d, ((-1)^omega(n/d))*numdiv(d)); \\ Antti Karttunen, Nov 17 2019
(PARI) for(n=1, 100, print1(direuler(p=2, n, (1 - 2*X)/(1 - X)^3)[n], ", ")) \\ Vaclav Kotesovec, Aug 22 2021
CROSSREFS
KEYWORD
sign,mult,easy
AUTHOR
Ilya Gutkovskiy, Oct 19 2019
STATUS
approved