Are there any natural $n$ that for $ \frac {2^{n+1}-1}{n+1}$ is natural?
4970
For $n \geq 2$, show that $n \nmid 2^{n}-1$
31174
Find the limit if it exists of $S_{n+1} = \frac{1}{2}(S_n +\frac{A}{S_n})$
33757
For what natural numbers is $n^3 < 2^n$? Prove by induction
63474
Showing $\sum_{i = 1}^n\frac1{i(i+1)} = 1-\frac1{n+1}$ without induction?
72511
If $n$ is an odd natural number, then $8$ divides $n^{2}-1$
39771
Is the natural log of n rational?
24572
Does $n \mid 2^{2^n+1}+1$ imply $n \mid 2^{2^{2^n+1}+1}+1$?
64941
Why is $1 - \frac{1}{1 - \frac{1}{1 - \ldots}}$ not real?
94983
Can an odd number $n$ divide $2^n-1$?
21781
Prove for any $a>1$ there exist a natural number, $N$, such that $a^n>n$ for all $n \ge N$
100232
Find equivalent of recurrent sequence $u_1=1$, $u_{n+1}=1+\frac n {u_n}$
28942
About Math notation: the set of the first $n$ natural numbers
35611
How can I show that $n! \leqslant \left(\frac{n+1}{2}\right)^n$?
52682
Is the power set of the natural numbers countable?
156766
Prove that $\sqrt{\frac{n}{n+1}}\notin \mathbb{Q}$
12423
"Closed" form for $\sum \frac{1}{n^n}$
2402
Does $\sin n$ have a maximum value for natural number $n$?