Finite or Infinite n in $φ(n)$
71108
Is there an integer $N>0$ such that $\varphi(n) = N$ has infinitely many solutions?
73454
Prove that $f$ has finite number of roots
84930
How to justify $\phi(n) \ge \sqrt{n}$
104549
When $d \mid n$, the number of elements of order $d$ in a cyclic subgroup of order $n$ is $\phi (d)$
115258
Find all positive integers $n$ such that $\phi(n)+\sigma(n)=2n$.
9651
Cardinality of cartesian product of an infinite set with N
137621
The Number of Topologies on a Finite Set
154796
Completeness of sequence of reals with finitely many nonzero terms
35547
Does $\{f_ng_n\}\to fg$ uniformly?
151928
How to prove that $N\setminus A$ is finite?
109034
Does a finite $[E:K]_s$ imply that $[E_s:K]$ is finite?
60284
Infinitely many positive integers $n$ such that $\phi(n) = \frac{n}{4}$?
139078
Infinite partition of $\mathbb N$ by infinite subsets
131163
There is a well ordering of the class of all finite sequences of ordinals
67295
Please check my proof for $N$ is infinite
73934
Subadditive sequences and the limit $\sup_{n\to\infty} a_n / n$
4512
Is there a direct, elementary proof of $n = \sum_{k|n} \phi(k)$?