On finite groups whose every proper normal subgroup is a union of a given number of conjugacy classes

Ali Reza Ashrafi, Geetha Venkataraman

Let $G$ be a finite group and $A$ be a normal subgroup of $G$. We denote by $ncc(A)$ the number of $G$-conjugacy classes of $A$ and $A$ is called $n$-decomposable, if $ncc(A)=n$. S…