Groups having 12 cyclic subgroups

Abstract

A finite group is said to be $n$-cyclic if it contains $n$ cyclic subgroups. For a finite group $G$, the ratio of the number of cyclic subgroups to the number of subgroups is known as the cyclicity degree of the group $G$ and is denoted by $cdeg(G)$. In this paper, we classify all $12$-cyclic groups. We also prove that the set of cyclicity degrees for all the finite groups is dense in $[0,1]$, which gives a solution to the problem asked by Tărnăuceanu and Tóth in [20] "For every $a\in [0,1]$, does there exist a sequence $(G_n)$ of finite groups such that ${\lim }_{n\to \infty }cdeg(G_n)=a$ "?

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