  In this note we introduce a determinant and then give its evaluating formula.
The determinant turns out to be a generalization of the well-known ballot and
Fuss-Catalan numbers, which is believed to be new. The evaluating formula is
proved by showing that the determinant coincides with the number of lattice
paths with (1,0), (0,1)-steps in the plane that stay below a boundary line of
rational slope.
