If $p$ is a prime then $p^2+26$ is not a prime
57275
On the primality of integers of the form $p^2+k$
86594
If $x^2 \equiv y^2 \pmod {p^r}$, where $p$ is an odd prime not dividing $x$ or $y$ then $x \equiv \pm y \pmod {p^r}$
110809
What can primes, except 2, 3, and 5, be congruent to $\pmod {30}$?
68221
Question regardles primes and the fundamental theorem of arithmetic
24988
Prove there exists $m > 2010$ such that $f(m)$ is not prime
34588
Number Theory: $p!+p=n^2$, $p$ = prime
79208
Is the number $-1$ prime?
34617
Number Theory: which primes are a sum of two squares?
38911
Squares in $\mathbb{Z}_p$ that are not squares in $\mathbb{Z}$
56328
Find p is the prime number which $\frac{p+1}{2}$ and $\frac{p^2+1}{2}$ both are square number.
143772
How can I algebraically prove that $2^n - 1$ is not always prime?
30134
For $a,n \in \Bbb N$, how to prove if $a^n-1$ is prime then $a=2$ and $n$ is prime?
80658
Prove that the number $19\cdot8^n+17$ is not prime, $n\in\mathbb{Z}^+$
131488
Show that $p^3+4$ is prime
95111
Elementary proof for $\sqrt{p_{n+1}} \notin \mathbb{Q}(\sqrt{p_1}, \sqrt{p_2}, \ldots, \sqrt{p_n})$ where $p_i$ are different prime numbers.
50781
$(n+1)$th prime $p_{n+1}$ less than or equal to $p_1p_2\dots p_n+1$
131385
How to provide a counterexample for if $n$ is prime, then $2^n -1$ is prime