Finite Groups with a Prescribed Number of Cyclic Subgroups II

Abstract

Tărnăuceanu described the finite groups $G$ having exactly $|G|-1$ cyclic subgroups. In "Finite Groups with a Prescribed Number of Cyclic Subgroups,", we used elementary methods to completely characterize those finite groups $G$ having exactly $|G|-\Delta$ cyclic subgroups for $\Delta =2,3,4$ and $5$. In this paper, we prove that for any $\Delta >0$ if $G$ has exactly $|G|-\Delta$ cyclic subgroups, then $|G|\le 8\Delta$ and therefore the number of such $G$ is finite. We then use the computer program GAP to find all $G$ with exactly $|G|-\Delta$ cyclic subgroups for $\Delta =1,\dots ,32$.

17 pages