The distribution of the number of subgroups of the multiplicative group

Greg Martin, Lee Troupe

Let $I(n)$ denote the number of isomorphism classes of subgroups of $(\mathbb{Z}/n\mathbb{Z}{)}^{\times }$, and let $G(n)$ denote the number of subgroups of $(\mathbb{Z}/n\mathbb{Z}{)}^{\times }$ counted as…