Find all positive integer that $2^{2^n}+5 $ is a prime number.
112120
Find all primes of the form $2^{2^n} + 5$ for a nonnegative integer n
81250
Infinitude of prime numbers
45700
How can I know if $2^{2^{2^{2^{2}}}}+1=?$ is prime?
38498
Find all primes $p$ such that $(2^{p-1}-1)/p$ is a perfect square
58418
Does there exist a set of exactly five positive integers such that the sum of any three distinct elements is prime?
111490
Proof that every number has at least one prime factor
68480
Proof by Induction: Prove that $2^n > n^2$, for all natural numbers greater than or equal to $5$
105442
Show that any prime divisor of $x^4+x^3+x^2+x+1$, with $x\in\mathbb{N}$, is $5$ or $1$ mod $5$
123296
Determine whether a number is prime
111037
Consider numbers of the type $n=2^m+1$. Prove that such an n is prime only if $n=F_K$ for some $ k \in N$, where $F_k$ is a Fermat Prime.
90806
Find all positive integers $n$ such that $n$ is divisible by all the positive integers less than or equal to $\sqrt{n}$
91069
Express an even number as a sum of primes
123033
Showing a number $n$ is prime if $(n-2)! \equiv 1 \pmod n$
5978
Prove that there exists only one prime number of the form $p^2−1$ where $p≥2$ is an integer
154475
Prove that if $2^n - 1$ is prime, then $n$ is prime for $n$ being a natural number
16660
Prove that any positive number has an $n$th root
59036
If $a^{n}-1$ is prime then $a=2$ and $n$ is prime?