OFFSET
1,2
COMMENTS
Dirichlet inverse of A008578.
LINKS
Ilya Gutkovskiy, Scatterplot of a(n) up to n=50000
MATHEMATICA
a[1] = 1; a[n_] := a[n] = -Sum[If[d > 1, Prime[d - 1] a[n/d], 0], {d, Divisors[n]}]; Table[a[n], {n, 65}]
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Mar 04 2022
STATUS
approved