OFFSET
1
COMMENTS
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..100000
FORMULA
Multiplicative with a(3^e) = 0, and for primes p <> 3, a(p^e) = 1 if e = 1, and 0 if e > 1.
a(n) = A008966(3*n).
a(n) = abs(A156277(n)).
From Amiram Eldar, Jan 03 2023: (Start)
Dirichlet g.f.: zeta(s)*(1-1/3^s).
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 9/(2*Pi^2) = 0.455945... (A088245). (End)
MATHEMATICA
a[n_] := If[SquareFreeQ[3*n], 1, 0]; Array[a, 100] (* Amiram Eldar, Dec 30 2022 *)
PROG
CROSSREFS
Characteristic function of A261034.
KEYWORD
nonn,mult
AUTHOR
Antti Karttunen, Dec 29 2022
STATUS
approved