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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
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