New posts in Elementary Number Theory

Two sets having the same subset sums.

Find the last two digits of $7^{100}-3^{100}$

$n$ is prime iff $\binom{n^2}{n} \equiv n \pmod{n^4}$?

A finite set of distinct positive numbers is special if each integer in the set divides the sum of all integers within the set.

USA TST 2018/P1: Prove that the $n^{\text{th}}$ smallest positive integer relatively prime to $n$ is at least $\sigma(n)$

Find all positive integers $n$ for which $1372n^4 - 3 $ is an odd perfect square.

Find the remainder when $\sum_{n=1}^{2015}{n^2\times2^n}$is divided by 23.

Prove that no points on a circle of radius $\sqrt{3}$ can have both $x$ and $y$ coordinates rational

Can an integer that is $3\pmod 7$ be expressed as a sum of two cubes?

How do I find integers $x,y,z$ such that $x+y=1-z$ and $x^3+y^3=1-z^2$?