Number of n X n nonnegative integer arrays with upper left 0 and lower right its king-move distance away minus 1 and every value increasing by 0 or 1 with every step right, diagonally se or down.

A252888

Number of n X n nonnegative integer arrays with upper left 0 and lower right its king-move distance away minus 1 and every value increasing by 0 or 1 with every step right, diagonally se or down.