Square equal to sum of three squares
15003
Pythagorean Quadruples:
72389
Positive integer $n$ such that $2n+1$ , $3n+1$ are both perfect squares
87505
binomial coefficient equal to sum
50128
Efficiently finding two squares which sum to a prime
115264
Find when three numbers have the same remainder when divided by the same number
19
Why is the square root of a sum not equal to the square root of each its addends?
122891
integer as sum of three binomials
126711
What is the square matrix $A$ equal to if $A=A^2$
135212
The square of an integer has form $3n$ or $3n+1$
134311
How to determine equation for $\sum_{k=1}^n k^3$
15403
Sum of square of function
23830
Proof that if $p\equiv3\,\left(\mbox{mod 4}\right)$ then $p$ can't be written as a sum of two squares
22840
The sum of the first $n$ squares is a square: a system of two Pell-type-equations
136582
Decomposing total sum of squares
93657
Proving “The sum of $n$ consecutive cubes is equal to the square of the sum of the first $n$ numbers.”
83910
Integer part of $\sqrt[3]{24+\sqrt[3]{24+\sqrt[3]{24+\cdots}}}$
62747
Use induction to prove a product of sums of squares is a sum of squares