Any product of primes in the form of 4n+1 is the sum of 2 relatively prime squares
75318
How do you prove that a prime is the sum of two squares iff it is congruent to 1 mod 4?
90921
Product of two primitive polynomials
69830
How often is $1+\prod_{k=1}^n p_k$ not prime?
117516
Prime trios of the form $p$,$p+2$,$p+4$
144779
The number of ways to represent $(n^2+n)/4$ as a sum of $n/2$ distinct integers in $1,\dots,n$
98440
Show that any non-negative rational integer may be written as the sum of two squares if it is of the form....
146512
Prove that for every prime number $p>3$, $4p^2+1$ can be written as the sum of three square numbers
118629
$p,q$ odd primes, $q\mid a^p-1\Rightarrow q\mid a-1$ or $\,2p\mid q-1$
155452
Prime factorization of square numbers
125188
how to prove $m^{\phi(n)}+n^{\phi(m)}\equiv 1 \pmod{mn}$ where m and n are relatively prime?
12365
Show that every prime $p>3$ is either of the form $6n+1$ or of the form $6n+5$
71482
Solve $p_4(x) = x^4 −(2m + 4)x^2 + (m−2)^2 $such that $p_4$ is a product of two non-constant integer-coeficient polynomials
131731
Primes that can't be written as sum of two squares. Mod
142580
Prove that a perfect square is either a multiple of $4$ or of the form $4q+1$.
92106
Prove that $n$ is a sum of two squares?
23544
Complete induction proof that every $n > 1$ can be written as a product of primes
157766
Are primes (ignoring $2$) equally likely to be $1~\text{or}~3\pmod 4$?