Tinyurl-style unique code: potential algorithm to prevent collisions

Question

I have a system that requires a unique 6-digit code to represent an object, and I\'m trying to think of a good algorithm for generating them. Here are the pre-reqs:

Answer 1

There is another method to get a similar result (jumping over the entire set of the values without repeating, nonconsequtively), without using the primes - by using maximum length sequences, which you can generate using specially constructed shift registers.