Is $k+p$ prime infinitely many times?
21383
Can every even integer be expressed as the difference of two primes?
47162
Proving there are infinitely many primes of the form $a2^k+1.$
106111
Understanding that there are infinitely many primes of form $4n+3$
54286
Let $p$ a prime number, then prove that : $\sum \limits_{k=0}^{p} \binom {p}{k} \binom{p+k}{k} \equiv 2^p +1 \pmod{p^2}$
78342
When is $\phi(n)$ a prime number?
97021
Do there exist two primes $p<q$ such that $p^n-1\mid q^n-1$ for infinitely many $n$?
53469
C(0, 1) has infinitely many prime ideals not of the form Mp
22441
Does the sum of reciprocals of primes converge?
124849
Notation/name for the number of times a number can be exactly divided by $2$ (or a prime $p$)
5978
Prove that there exists only one prime number of the form $p^2−1$ where $p≥2$ is an integer
62821
Infinitely many primes of the type 5 mod 6.
49893
"Are there finitely or infinitely many Fermat primes?": decidable?
75528
$x^2-x+1$ has a root $\!\bmod p\,$ for infinitely many primes $p$
53525
Infiniteness of non-twin primes.
63129
Infinite number of $k$ satisfying $p_{k+1} - p_{k} > 2$?
124009
Every prime number divide some sum of the first $k$ primes.
81250
Infinitude of prime numbers