compute \begin{vmatrix} \lambda & 1 & & & & \\ n & \lambda & 2 & & & \\ & \ddots & \ddots & \ddots & & \\ & & \ddots & \ddots & \ddots & \\ & & & 2 & \lambda & n \\ & & & & 1 & \lambda \end{vmatrix}
I tried to find some recurrence relations, but I failed. I added all the rows except the first row to the first row, but I can't find any useful equations. How to compute it?