Is the following proposition true? If yes, how do we prove it?
Proposition Let $D$ be a non-square integer such that $D \equiv 0$ (mod $4$) or $D \equiv 1$ (mod $4$). Let $\Phi_1,\dots,\Phi_{\mu}$ be the system of genus characters of discriminant $D$. Then the number of genera of discriminant $D$ is $2^{\mu - 1}$.
