Are there infinitely many Substrimes in any base?
93721
Are numbers in which all substrings are primes finite regardless of base?
116768
Problem 5, sec. 13 in Munkres' Topology, 2nd ed.: How to prove the assertion if $\mathscr{A}$ is a subbasis?
133266
If $(X, \mathcal{T})$ has a countable subbasis, then it has a countable basis
152503
Rational numbers as vectors in infinite dimensional space with the basis $( \log 2,\log 3, \log 5, \log 7, \dots, \log p, \dots) $
132132
Are there infinitely many primes of the form $6^{2n}+1$ or only finitely many?
63390
Infinite algebraic extensions of $\mathbb{Q}$
6484
Polynomials in one variable with infinitely many roots.
112910
Is the set of real numbers really uncountably infinite?
75970
$\mathbb Z[1/2]$ is not finitely generated?
63129
Infinite number of $k$ satisfying $p_{k+1} - p_{k} > 2$?
100072
Can we add an uncountable number of positive elements, and can this sum be finite?
35821
Infinitely many primes for quadratic residues
53363
Ultralimit of an eventually constant generalized sequence
73934
Subadditive sequences and the limit $\sup_{n\to\infty} a_n / n$
115004
If $x\notin\mathbb Q$, then $\left|x-\frac{p}{q}\right|<\frac{1}{q^2}$ for infinitely many $\frac{p}{q}$?
49893
"Are there finitely or infinitely many Fermat primes?": decidable?
126552
Number of subfields of finite field