$n^4 + 4^n$ is a not a prime
3500
Compositeness of $n^4+4^n$
144622
Proof: If no prime less than or equal to $\sqrt{n}$ divides $n$, then $n$ is a prime
40968
show if $n=4k+3$ is a prime and ${a^2+b^2} \equiv 0 \pmod n$ , then $a \equiv b \equiv 0 \pmod n$
77806
Proving if $a$ is not a multiple of prime $p$, then an integer $b$ exists such that $p^b - 1$ is a multiple of $a$
25232
Is this formula for the $n^{th}$ prime number useful?
45461
Is there a prime which is the form of $10^n + 1$ except $2, 11, 101$?
82485
Show that the set of non zero rationals is not a cyclic group under multiplication.
131731
Primes that can't be written as sum of two squares. Mod
70066
Show that product of primes, $\prod_{k=1}^{\pi(n)} p_k < 4^n$
92737
primes whose difference is a multiple of $n$
109305
Non-existence of natural numbers such that $\sqrt{n} +\sqrt{n+1} <\sqrt{x} +\sqrt{y} <\sqrt{4n+2}$
19979
Why does $p^2+8$ prime imply $p^3+4$ prime
19761
Show for prime numbers of the form $p=4n+1$,  $x=(2n)!$ solves the congruence $x^2\equiv-1 \pmod p$. $p$ is therefore not a gaussian prime.
30134
For $a,n \in \Bbb N$, how to prove if $a^n-1$ is prime then $a=2$ and $n$ is prime?
106111
Understanding that there are infinitely many primes of form $4n+3$
78342
When is $\phi(n)$ a prime number?
152299
Proving $a^{n-1} \equiv 1 \mod n $ when n is not prime.