Sum of radicals is rational only for perfect squares
106716
The sum of square roots of non-perfect squares is never integer
10008
Proof that the nth root of a rational s/t is irrational unless s and t are perfect nth powers
10920
$\delta_2(n)$ the sum of the squares of the positive divisors of $n$.
41641
$(n-7)(n+7)=$ some perfect square
21906
Show $3^m + 3^n +1$ cannot be a perfect square for $m,n$ being positive integers.
104494
$m$ doesn't come in the sequence $a_n=[n+\sqrt{n}+\frac{1}{2}]$ iff m is a perfect square
152643
$(xy + 1)(yz + 1)(zx + 1) $ is a perfect square if and only if each factor is
54355
$1+x+\ldots+x^n$ perfect square
83145
Sum of rational numbers
5287
Representing every positive rational number in the form of $(a^n+b^n)/(c^n+d^n)$
133164
Rational solutions for $x^2+y^2=3$
147848
Integer $x$ for which $x^4+x^3+x^2+x+1$ is perfect square.
86285
Given positive integers $ x , y$ and that $3x^2 + x = 4y^2 +y$ Prove that $x-y$ is a perfect square
78593
Prove that the product of four consecutive positive integers plus one is a perfect square
72389
Positive integer $n$ such that $2n+1$ , $3n+1$ are both perfect squares
101835
Which rationals can be written as the sum of two rational squares?
18932
Squares in arithmetic progression