Showing that $ U(2^n) $ is not a cyclic group for $ n \geq 3 $
14003
$(\mathbb{Z}/2^n \mathbb{Z})^*$ is not cyclic Group for $n\geq 3$
102622
K is a subgroup of G. Show that K is not a normal subgroup
106123
Is there a finite abelian group $G$ such that $\textrm{Aut}(G)$ is abelian but $G$ is not cyclic?
18182
An abelian group $G$ with ${\rm Aut}(G)$ non-abelian
94747
Show that the rings $2\mathbb{Z}$ and $3\mathbb{Z}$ are not isomorphic.
157841
Existence of a non-abelian group of order $p^n$.
135039
${\rm Aut}(G)$ is cyclic $\implies G$ is abelian
82485
Show that the set of non zero rationals is not a cyclic group under multiplication.
48585
Proving that if $G/Z(G)$ is cyclic, then $G$ is abelian
67383
Prove that $G'$ is not planar.
144258
How to show a group is cyclic?
135241
Show that $\mathbb{Z}/n^2\mathbb{Z}$ is not isomorphic to other group
135808
Show that there is a positive integer $n$ such that $G \cong \ker(\phi^{n}) \times \phi^{n}(G)$
151025
If G is a group of order n=35, then it is cyclic
119545
Nonzero rationals under multiplication are not a cyclic group
64130
Prove that $\mathbb{Q}^{\times}$ not isomorphic to $\mathbb{Z}^{n}$
129485
A subgroup of a cyclic group is cyclic - Understanding Proof