Subgroups of index $2$ (question)
75568
Subgroup of index $2$ is Normal
103829
Find the subgroups of A4
142938
Sylow 2-subgroups of the group $\mathrm{PSL}(2,q)$
88344
Order of a group and subsequent subgroups
91997
Product of two subgroups the whole group?
110708
On proving that a finitely generated group has a finite number of subgroups with index $n$.
131516
Subgroup generated by n-th powers of elements
91966
Find all subgroups of group
133001
$G$ simple group and there exists a subgroup of index $n$. Show that: $|G|$ divides $n!/2$
19229
How to find all groups that have exactly 3 subgroups?
58863
Proof that $A_n$ the only subgroup of $ S_n$ index $2$.
153797
Is a quotient group a subgroup?
53409
Show group of order $4n + 2$ has a subgroup of index 2.
86336
For $G$ group and $H$ subgroup of finite index, prove that $N \subset H$ normal subgroup of $G$ of finite index exists
107935
If $G$ is a group, $H$ is a subgroup of $G$ and $g\in G$, is it possible that $gHg^{-1} \subset H$?
12667
How many subgroups of order $n$ does $D_n$ have?
59138
Subgroups of $S_4$ isomorpic to $S_2$