OFFSET
1,9
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
FORMULA
a(1) = 1; for n > 1, a(n) = -Sum_{d|n, d<n} A175851(n/d)*a(d).
MATHEMATICA
b[n_] := If[n < 3, 1, n - NextPrime[n + 1, -1] + 1];
a[n_] := a[n] = If[n == 1, 1, -Sum[b[n/d] a[d], {d, Most@Divisors[n]}]];
Array[a, 100] (* Jean-François Alcover, Feb 17 2020 *)
PROG
CROSSREFS
KEYWORD
sign
AUTHOR
Antti Karttunen, Jun 13 2018
STATUS
approved