OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..10000
FORMULA
a(n) is multiplicative with a(2)= -5, a(4)= 4, a(2^e)= 0 if e>2. a(p)= -p^2, a(p^e)= 0 if e>1, p>2.
G.f. A(x) satisfies x * (1 - x) = Sum_{k>=1} k^2 * A(x^k).
MATHEMATICA
f[p_, e_] := If[e == 1, -p^2, 0]; f[2, e_] := Switch[e, 1, -5, 2, 4, _, 0]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, May 10 2023 *)
CROSSREFS
KEYWORD
sign,mult
AUTHOR
Seiichi Manyama, Apr 01 2023
STATUS
approved