Proper notation for a generalization of the Liouville $\lambda$ function

Question

Can someone suggest good notation for a simple generalization of the Liouville Lambda function, $\lambda(n) = (-1)^{\Omega(n)}?$

I would like to express that $\lambda_{k,r}(n) = 1$ if $\Omega(n)\equiv r~(\mod k)$ and zero otherwise.

I thought of expressing this in terms of the Dirichlet principal character. Not sure if that is appropriate.

Thanks!