Question 124
for a non-negative integer $n$ we call a permutation $\left(a_{0}, a_{1}, \ldots, a_{n}\right)$ of $\{0,1, \ldots, n\}$ Quadratic as $k+a_{k}$ A square is for $k=0,1, \ldots, n$. proof that for each non-negative whole $n$ A quadratic permutation of $\{0,1, \ldots, n\}$ exists.