So, take the procedure d := proc (n) options operator, arrow; piecewise(n = 0, 1, `mod`(n, 2) = 1, 2, `mod`(n, 4) = 2, 4, `mod`(n, 8) = 4, 8, `mod`(n, 16) = 8, 16, 32) end proc I tried to use unapply, but it doesn't work at all and gives strange results.. it appears to evaluate the mod beforehand. So, just evaluting d(n) above works fine > l := [seq(d(n), n = 0 .. 16)]; l := [1, 2, 4, 2, 8, 2, 4, 2, 16, 2, 4, 2, 8, 2, 4, 2, 32] However, simplify(d(n)) destroys the function. Also, prod(d(n),n=0..m) returns the wrong values, mul(d(n),n=0..5) works for a finite value such as 5, but does not work symbolically... what gives, why is maple behaving so badly with the mod operator? Any help would be greatly appreciated.