How to prove that $3^i5^j$ can never be a perfect number?
42932
Prove that $p^j q^i$ cannot be a perfect number for $p, q$ odd, distinct primes.
154133
Flawed proof by induction that $a^{n-1}=1$
133017
Prove that $n^n>1\times3\times5\times7\times \dots\times(2n-1)$
135955
Prove: The positive integers cannot be partitioned into arithmetic sequences (using Complex Analysis)
33792
Numbers to the Power of Zero
17306
To find all $n$ such that $(n-1)!+1$ is a perfect power of $n$
103581
Which positive integers can NOT be written as a sum of consecutive positive integers
144132
The number $2^{3^n}+1$ is divisible by $3^{n+1}$ and not divisible by $3^{n+2}$.
33866
Show that $n$ does not divide $2^n - 1$ where $n$ is an integer greater than $1$?
45911
Prove that none of $\{11, 111, 1111,\dots \}$ is the perfect square of an integer
85959
How do I prove that among any $5$ integers, you are able to find $3$ such that their sum is divisible by $3$?
93948
Is my proof correct? $p_1p_2p_3\cdots p_n+1)$ cannot be the square of an integer
8978
Who can prove that a triangular number cannot be a cube, fourth power or fifth power?
32524
Flawed proof that all positive integers are equal
116054
The number $(3+\sqrt{5})^n+(3-\sqrt{5})^n$ is an integer
137808
$n^2 + 3n +5$ is not divisible by $121$
147920
Infinite powering by $i$