$Z(D_{2n})=\{e\}$ if $n\ge 3$ is odd
88304
Center of $D_6$ is $\mathbb{Z}_2$
35184
If $z_n \to z$ then $(1+z_n/n)^n \to e^z$
102175
$Z=XY$, $E_Z[Z]$, $E_{X,Y}[XY]$
6827
To identify field $Z[i]/(3)$
87664
Combination of $n$ letter out of $3n$.
94291
$\frac{2^{2n}}{2n} \le {2n \choose n}$?
58205
$ N $ normal in a finite group $ G $, $ |N| = 5 $ and $ |G| $ odd. Why is $ N \subseteq Z(G) $?
97411
If $x^n=y^n$ and $n$ is odd then $x=y$
78564
Prove: $D_{8n} \not\cong D_{4n} \times Z_2$.
128306
Show that for all $n ∈ Z$, $2n^3 + 3n^2 + n$ is divisible by both 2 and 3.
37928
Isomorphism between $D_{2n}/Z(D_{2n})$ and $D_n$
103504
Weird $3^n$ in an identity to be combinatorially proved
13525
Prove: If $n=2^k-1$, then $\binom{n}{i}$ is odd for $0\leq i\leq n$
69575
If $ad$ and $bc$ are odd and even, respectively, then prove that $ax^3+bx^2+cx+d$ has an irrational root.
129605
$ 2g(z)=g(\frac{z}{2}) + g(\frac{z+1}{2})$
28722
Prove that $H$ is a abelian subgroup of odd order
98352
If $k|n$, then $D_{2n}/\langle{r^k}\rangle\cong D_{2k}$