OFFSET
1
COMMENTS
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Dirichlet Generating Function.
Wikipedia, Dirichlet series.
FORMULA
Multiplicative with a(p) = a(p^2) = -1, a(p^3) = 1, and a(p^e) = 0 for e >= 4. - Amiram Eldar, Dec 25 2022
MATHEMATICA
nmax = 100; A271102 = Table[DivisorSum[n, Abs[MoebiusMu[#]]*MoebiusMu[n/#] &], {n, 1, nmax}]; Table[DivisorSum[n, MoebiusMu[n/#]*A271102[[#]] &], {n, 1, nmax}]
nmax = 100; A007427 = Table[DivisorSum[n, MoebiusMu[#]*MoebiusMu[n/#] &], {n, 1, nmax}]; Table[DivisorSum[n, Abs[MoebiusMu[n/#]]*A007427[[#]] &], {n, 1, nmax}]
f[p_, e_] := 0; f[p_, 1] = f[p_, 2] = -1; f[p_, 3] = 1; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Dec 25 2022 *)
PROG
(PARI) for(n=1, 100, print1(direuler(p=2, n, (1-X^2)*(1-X))[n], ", ")) \\ Vaclav Kotesovec, Jun 14 2020
CROSSREFS
KEYWORD
sign,mult
AUTHOR
Vaclav Kotesovec, Apr 08 2019
STATUS
approved