Proving $\phi(m)|\phi(n)$ whenever $m|n$
52565
Prove that if $d \mid n \in \mathbb{N}$, then $\varphi(d) \mid \varphi(n)$.
9753
How to solve the equation $\phi(n) = k$?
4530
For which natural numbers are $\phi(n)=2$?
46741
Prove that $n$ divides $\phi(a^n -1)$ where $a, n$ are positive integer without using concepts of abstract algebra
88425
Prove that $\,\sqrt [n] n < 1 + \sqrt{\frac{2}{n}}\,$
68385
Prove that $ \frac{n}{\phi(n)} = \sum\limits_{d \mid n} \frac{\mu^2(d)}{\phi(d)} $
30630
Proving ${n \choose p} \equiv \Bigl[\frac{n}{p}\Bigr] \ (\text{mod} \ p)$
94558
Show that $\phi(mn) = \phi(m)\phi(n)\frac{d}{\phi(d)}$
39073
Proving that: $\forall n \in \mathbb{N} :|f^{(n)}(x)|\leq \frac{1}{n+1}$
96152
Showing that $a^n - 1 \mid a^m - 1 \iff n \mid m$
115258
Find all positive integers $n$ such that $\phi(n)+\sigma(n)=2n$.
134812
Proving that if $\sum\|f_n-e_n\|^2< 1$, $\{f_n\}$ is a complete sequence
111951
Prove $\binom{n}{m}\binom{m}{k} = \binom{n}{k}\binom{n-k}{m-k}$
59724
Proving that $x_n\to L$ implies $|x_n|\to |L|$, and what about the converse?
149509
What method would you go through to find an $n$ such that $\phi(n)=100$?
52951
Find all $n \in \mathbb{Z^+}$ such that $\phi(n)=4$
49806
Prove that $\frac{R/ \ker \phi}{(\ker \phi + J)/ \ker \phi} \cong \frac{S}{\phi(J)}$