I am trying to prove the following statement,
Let ω be a complex nth root of unity. We say that ω is a primitive nth root if $\omega^m\neq1$ for any positive $m < n$. Prove that for all $n\in\mathbb{N}$, the sum of the primitive complex nth roots of unity is $\mu(n)$.
I know this somehow involves the Mobius inversion formula but aside from this I do not know how to progress. Any help would be greatly appreciated!