Let A= [1, 1/51; 0, 1]. If B= [1, 2; -1, -1] A [-1, -2; 1, 1], then the sum of all the elements of the matrix Σ_n=1^50 B^n is equal to

Let $\displaystyle A=\left[\begin{array}{cc}1 & \frac{1}{51} \\ 0 & 1\end{array}\right]$. If $\displaystyle B=\left[\begin{array}{cc}1 & 2 \\ -1 & -1\end{array}\right] A\left[\begin{array}{cc}-1 & -2 \\ 1 & 1\end{array}\right]$, then the sum of all the elements of the matrix $\displaystyle \sum_{n=1}^{50} B^n$ is equal to