1.7 Multiplicity of Boolean functions There are four single-variable Boolean functions of which only two actually depend of the input variable x (x and x'). Similarly, there are 16 two-variable function of which only 10 depend on both variables (exclude x, x', y, y', 0, and 1). a. How many three-variable Boolean functions are there, and how many of them actually depend on all three variables? b. Generalize the result of part a for n-variable functions. Hint: You must subtract from the number of n-variable functions all the ones that depend on n - 1 or fewer variables