Here's some code and analysis related to random numbers. Here are some random facts about pseudorandom number generation. The Birthday Paradox.
Irreversible generators can have multiple states map to the same next state.
And so on. This makes all values occur with equal frequency in reversible generators. Well, write a little program with a loop for x and a loop for y, generate all possible values, and see. Here are some other random number generator related pages. I'm working on a paper about evaluating hash functions .