3
votes
0answers
20 views

How to show $\{a^n \bmod \alpha\}_{n \in \mathbb{N}}$ is dense in $[0,\alpha]$ if $a > 1$ is trancendental over ${\mathbb Q}[\alpha]$

How to show $\{a^n \bmod \alpha\}_{n \in \mathbb{N}}$ is dense in $[0,\alpha]$ if $a > 1$ is trancendental over ${\mathbb Q}[\alpha]$? If $a$ is transcendental over ${\mathbb Q}[\alpha]$ then the ...
3
votes
1answer
91 views

The set $\{\frac{3^m}{\alpha^n}:\;m,n\in\mathbb Z\}$ is dense in $\mathbb R_+$

This seems that the set $$\left\{\frac{3^m}{\alpha^n}:\;m,n\in\mathbb Z\right\}$$ is dense in $\mathbb R_+$ (the set of positive real numbers), but I can not find the proof. How to prove this? Edit ...
4
votes
0answers
424 views

Convergent sum with primes

If $f(n)$ is a strictly increasing elementary function from the reals to the reals, and $p(n)$ is the $n$'th prime number. Is there any $f(n)$ such that $\sum_{n=1}^\infty\frac{1}{f(p(n))}$ is ...