OFFSET
1,3
COMMENTS
Inverse Moebius transform of A308077.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..20000
FORMULA
G.f. A(x) satisfies: A(x) = x / (1 - x) - Sum_{k>=2} (-1)^k * A(x^k).
MATHEMATICA
a[n_] := a[n] = 1 - DivisorSum[n, (-1)^# a[n/#] &, # > 1 &]; Table[a[n], {n, 1, 81}]
PROG
(PARI) lista(nn) = {my(va = vector(nn)); for (n=1, nn, va[n] = 1 - sumdiv(n, d, if (d>1, (-1)^d*va[n/d])); ); va; } \\ Michel Marcus, May 22 2020
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, May 21 2020
STATUS
approved