n  = total # bits per sample
L1 = # bits   set on average on  left-side of AND/OR
L0 = # bits unset on average on  left-side of AND/OR
   = n - L1
R1 = # bits   set on average on right-side of AND/OR

##</code><code>##

AND : L1 * R1 / n

OR  : L1 + L0 * R1 / n = L1 + (n - L1) * R1 / n
                       = L1 + R1 - L1  * R1 / n
                       = L1 * ( 1 - R1 / n ) + R1