Question 37
Find a formula for the sum of the squares of the numbers in the $n$th row of Pascal's triangle (i.e. the numbers $\left(\begin{array}{l}n \\ 0\end{array}\right),\left(\begin{array}{l}n \\ 1\end{array}\right), \ldots,\left(\begin{array}{l}n \\ n\end{array}\right)$ ).