Hey shlosmem1.

Your relation in this case is (Ai XOR Bi) = 1 for some bit position i for less than 2. Basically this is a combinatoric argument where you can have:

0 difference (same numbers)

1 difference (8 possible differences)

2 difference (8C2 possible differences or 28 differences).

This means that for every number you have 1 + 8 + 28 or 37 possible numbers for each input that are "similar".

Can you take it from there?