Why $ D_n$ is not simple ?
6134
Some Subgroup of Dihedral Group is Normal
152478
Is there a homeomorphism between the $n$-dimensional cube to the $n$-dimensional simplex that doesn't create hard corners?
72420
Is $\mathbb{N}$ impossible to pin down?
144819
Proving $P(n) =n^{\phi(n)} \prod\limits_{d \mid n} \left(\frac{d!}{d^d} \right)^{\mu(n/d)}$
117020
Regular $n$-gon in the plane with vertices on integers?
102042
If $X_n \stackrel{d}{\to} X$ and $c_n \to c$, then $c_n \cdot X_n \stackrel{d}{\to} c \cdot X$
14827
RSA: Fast factorization of N if d and e are known
134440
An unexpected application of non-trivial combinatorics
44841
Complexity of $T(n) = 2T(n/2) + n$
131306
Prove that a group of order $2^5 \cdot 7^5$ is not simple
114277
Proving in Discrete Structures Problem that $2^N = \binom{N}{0} + \binom{N}{1} + \binom{N}{2} + \dots + \binom{N}{N}$
93029
Prove that when $d$ is in $\mathbb{Q} \setminus\mathbb{Z}$, $\mathbb{Z}[\sqrt{d}]$ is not a finitely generated abelian group.
85076
Is it true that $d(x,Y)=d(x,y_0)$ for some $y_0 \in Y$ when $Y$ is closed?
35948
How to prove $D^n/S^{n-1}\cong S^n$?
14693
$d = \gcd(c,m),\ ac≡bc\pmod{\! m}\Rightarrow a≡b\pmod {\!m/d}\ $ [Congruence Cancellation & Division Rule]
52157
Prove that $d(n)\leq 2\sqrt{n}$
124848
Why $O(n)$ has exactly two connected components?