Proper condition on the dihedral group Is there a theream which is a condition on $n\in\mathbb N$ that says when the dihedral group, $D_{n}$, has non-cyclic subgroups?
After spending some time figuring a condition I tried to find some similar thread but didn't find any.

Any cyclic group has unique subgroup of any order which is divisior of its order 
Now in $D_n$  How many subgroup of order 2?
They are at least n . 
SO for n>1
