Show that $2^n-1 \neq k^y$ for odd $y$
104920
Can we find positive integers $a$ and $k \geq 2$ with $2^n - 1 = a^k$?
66358
Prove by mathematical induction that $2n ≤ 2^n$, for all integer $n≥1$?
54442
Sum of $k {n \choose k}$ is $n2^{n-1}$
91877
Let $|x|\leq1, |y|\leq 1$. Show that$0 \leq x^{2}+y^{2} -2x^{2} y^{2}+2xy \sqrt{1-x^{2}} \sqrt{1-y^{2}} \leq 1$
513
If n is an odd integer, show there exists a positive integer k such that 2^k mod n = 1.
46102
Prove that $2^n +1$ in never a perfect cube
22093
How to show $a^{2^n}+1 \mid a^{2^m}-1$?
77464
Prove that ${x dy - y d x\over x^2 + y^2}$ is not exact
15838
Induction Proof that $x^n-y^n=(x-y)(x^{n-1}+x^{n-2}y+\ldots+xy^{n-2}+y^{n-1})$
51858
Showing $\gcd(2^m-1,2^n+1)=1$
94389
Proving formula for product of first n odd numbers
148455
Show that if $(a,n)=d>1$ and $k$ is any positive integer, then $a^k\not\equiv 1\pmod{n}.$
92166
Number of odd binomial coefficients is a power of $2$
87665
Proving $x^n - y^n = (x-y)(x^{n-1} + x^{n-2} y + ... + x y^{n-2} + y^{n-1})$
31295
$x+y\sqrt{2}$ infimum ($x,y\in \mathbb{Z}$)
139503
How to prove $|a+b|^k \leq 2^{k-1} (|a|^k+|b|^k)$?
33344
A different way to show that $a^k-1 \mid a^n-1$ if $k\mid n$?