OFFSET
1
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) = 0, and a(p^e) = (-1)^e for e >= 2. - Amiram Eldar, Dec 25 2022
MATHEMATICA
Table[DivisorSum[n, Boole[Max[FactorInteger[#][[All, 2]]] < 3] * LiouvilleLambda[n/#]&], {n, 1, 100}]
f[p_, e_] := (-1)^e; f[p_, 1] := 0; 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^3)/(1-X^2))[n], ", ")) \\ Vaclav Kotesovec, Jun 14 2020
(PARI)
A212793(n) = factorback(apply(e->(e<=2), factor(n)[, 2]));
CROSSREFS
KEYWORD
sign,mult
AUTHOR
Vaclav Kotesovec, Apr 08 2019
EXTENSIONS
Data section extended up to a(108) by Antti Karttunen, Jul 14 2022
STATUS
approved