with (x)j = x(x+ 1) · · · (x+ j − 1) being the usual rising factorial. The evaluation (1) was found by Mills, Robbins and Rumsey [3] in connection with some of their work on plane partitions. Their original proof was “quite complicated.” In [1], George Andrews gave another proof. The main idea of his proof was to exhibit a triangular matrix En, with 1’s on the diagonal, for which MnEn is triang...