number generator

[cesco]

> Since people are posting their solutions now (originally only hints
> were provided for the homework problem), here's mine:

Well, I never really said it was a homework problem. Sure there are
more implications to my question that I had first imagined and I'm
really happy I could get so many insights but the question did
originate from a real problem I was facing in my research.

Thanks to everyone for the wonderful thread so far
Francesco