Number of Switching Functions
l2
ln = 1: 22 = 4
ln = 2: 24 =16
ln = 3: 28 = 256
ln = 4: 216 = 65,536
ln = 5: 232 = 4,294,967,296
ln = 6: 264 = 18,446,744,073,709,551,616

2n
Each level squares the previous, since

 2     = 2     = 2       = (2   )


2n+1
2.2n
2n+2n
2n
2