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A332685
a(n) = Sum_{k=1..n} mu(k/gcd(n, k)).
3
1, 2, 1, 2, 0, 2, 0, 0, -1, 0, 0, 0, -1, -2, -2, -3, 0, -4, -1, -5, -4, -2, 0, -8, -3, -4, -4, -7, 0, -8, -2, -10, -5, -4, -4, -13, 0, -5, -4, -13, 1, -15, -1, -9, -10, -5, -1, -22, -4, -12, -5, -11, -1, -19, -6, -17, -6, -4, 1, -28, 0, -8, -12, -18, -6, -19, 0, -12, -5, -17
OFFSET
1,2
COMMENTS
Inverse Moebius transform of A112399.
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
KEYWORD
sign
AUTHOR
Ilya Gutkovskiy, Feb 19 2020
STATUS
approved