Popovici (1963) (see link), created a way to extend the Mobius function, $\mu(n)$, to the complex plane.
The Mobius $\mu(n)$ function is such that:
$\frac{1}{\zeta{(s)}}=\sum_{n=1}^{\infty}\frac{\mu(n)}{n^s}$
With Popovici's extension, $\mu_k(n)$, we get a generalization:
$\frac{1}{\zeta{(s)^k}}=\sum_{n=1}^{\infty}\frac{\mu_k(n)}{n^s}$, where $μ_k=μ∗...∗μ$ taken $k$ times on a Dirichlet convolution is Popovici’s function.
My question is..., how about $\zeta{(s)}^3$? Does his generalization of $\mu(n)$ work in this case?
And what the function $\mu_{-3}(n)$ would be in this case?