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15 votes
4 answers
2k views

Square roots and prime numbers

Definitions: Here I present a novel conjecture using basic mathematical tools like the sum of the divisors of an integer $n$ called $\sigma(n)$, the sum of the squares of the positive divisors of n ...
Sulfura's user avatar
  • 127
11 votes
2 answers
614 views

Jacobi symbols for two-square sums of primes

Given a prime $p\equiv 1\pmod 4$, Fermat's two-squares theorem discovered by Girard states that there exists two integers $A,B$ such that $p=A^2+B^2$. For all primes up to $10^7$ the integers $A$ and $...
Roland Bacher's user avatar
7 votes
2 answers
2k views

Sums of squares of primes [closed]

Question: What is the least number that is a sum of three squares of primes in exactly six ways? ... I know it is not research mathematics. Happy new year! EDIT: Now that it is answered I should ...
Andreas Thom's user avatar
  • 25.5k
5 votes
0 answers
229 views

Can we write each positive integer as $x^2+y^2+\varphi(z^2)$?

As odd squares are congruent to $1$ modulo $8$, any integer of the form $4^k(8m+7)$ with $k,m\in\mathbb N=\{0,1,2,\ldots\}$ cannot be written as the sum of three squares. To avoid such congruence ...
Zhi-Wei Sun's user avatar
  • 15.6k
8 votes
1 answer
416 views

Every odd integer greater than $1$ is of the form $a+b$ with $a^2+b^2$ being prime

Let $m$ be an odd integer greater than $1$. Is it true that there are positive $a, b$ such that $m=a+b$ and $a^2+b^2$ is a prime number? It seems that for every odd $m$ there are many $(a,b)\in \...
Konstantinos Gaitanas's user avatar
0 votes
1 answer
612 views

Number of fixed points in Zagier's involution (Fermat's Theorem) [closed]

Zagier's has found a famous one sentence proof for Fermat's theorem on sums of two squares. It centers on the following involution of the set $S= \lbrace (x,y,z) \in N^3: x^2+4yz=p \rbrace $ having ...
Toastgeraet's user avatar
21 votes
1 answer
1k views

Primes that are sums of two squares with constraints on the squares

It is well known that there are infinitely many primes of the form $a^2+b^2$ (namely all primes congruent to $1$ modulo $4$). On the other hand, Euler raised the problem as to whether there are ...
Kai's user avatar
  • 213
5 votes
1 answer
727 views

Sum of two squares and implication of Bunyakovsky conjecture

Bunyakovsky's conjecture states that a polynomial with integer coefficients takes infinitely many prime values at integers, unless this is impossible for trivial reasons. Let $a_1(x), a_2(x), a_3(x), ...
joro's user avatar
  • 25.4k
7 votes
2 answers
426 views

Divisor sums over values of binary forms of primes

Let $\tau$ be the divisor function, that is $$ \tau(n)=\sharp\{d \in \mathbb{N}, d|n\}. $$ I was wondering if anyone has ever proved an asymptotic estimate for the sum $$S(x):=\sum_{p,q\leq x}\tau(p^...
Dr. Pi's user avatar
  • 3,062
6 votes
1 answer
653 views

On permuted sum of squares of primes in a list

We want to pick a set of distinct primes (if not possible, then just positive numbers) $p_1,p_2,\dots,p_k$ such that there exists $t$ permutations, $\sigma_1(\cdot)$,$\sigma_2(\cdot),\dots,\sigma_t(\...
Turbo's user avatar
  • 13.9k
1 vote
0 answers
255 views

Confirm/refute $f(x)$ where $f(x) = $x-th Mersenne prime ($M_p$) where $x$ is [1,2,3,4,5,6,7...]

While tinkering with numbers, I found $n=f(x)$ where $n = \sigma(\sigma(n)-n)$ and $x \neq p$ where $p$ is a Mersenne prime exponent, but I need help input in regard to improving accuracy. First off, ...
JohnWO's user avatar
  • 131
3 votes
3 answers
958 views

solutions to equation mod a prime

I know that characterizing the solutions to an equation in a finite field is generally difficult, but I was wondering if anyone had anything to say about the equation (ab)^2 + a^2 + b^2 = 0 mod p I ...
Sarah's user avatar
  • 39