OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
a(n) is multiplicative with a(2)= -3, a(4)= 2, a(2^e)= 0 if e>2. a(p)= -p, a(p^e)= 0 if e>1, p>2.
a(1) = 1, a(2) = -3; a(n) = -n * Sum_{d|n, d < n} a(d) / d.
G.f. A(x) satisfies x * (1 - x) = Sum_{k>=1} k * A(x^k).
a(n) = n*mu(n)-n*mu(n*2^(n mod 2)/2)*((n+1) mod 2)/2. - Wesley Ivan Hurt, Jun 09 2023
MATHEMATICA
a[n_] := n * MoebiusMu[n] - If[OddQ[n], 0, MoebiusMu[n/2]*n/2]; Array[a, 100] (* Amiram Eldar, May 09 2023 *)
PROG
(PARI) a(n) = n*moebius(n)-if(n%2, 0, n/2*moebius(n/2));
CROSSREFS
KEYWORD
sign,mult
AUTHOR
Seiichi Manyama, Mar 31 2023
STATUS
approved
