Looking for an algorithm to spit out a sequence of numbers in a (pseudo) random order

Question

Suppose I have a sequence of numbers: {n, n+1, n+2, ... n + m}

Without storing the numbers ahead of time I want to create a function f(), which given the sequence {1,2,3

Answer 1

You can fit a polynomial to the selected sequence; I'd guess that's what your coworker showed you. It won't save space compared to just remembering the permutation, though.