OFFSET
1,2
COMMENTS
Inverse Moebius transform of A112399.
LINKS
Ilya Gutkovskiy, Scatterplot of a(n) up to n=10000
FORMULA
a(n) = Sum_{k=1..n} mu(lcm(n, k)/n).
a(n) = Sum_{d|n} A112399(d).
MATHEMATICA
Table[Sum[MoebiusMu[k/GCD[n, k]], {k, 1, n}], {n, 1, 70}]
PROG
(PARI) a(n) = sum(k=1, n, moebius(k/gcd(n, k))); \\ Michel Marcus, Feb 21 2020
CROSSREFS
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Feb 19 2020
STATUS
approved