Mapping two integers to one, in a unique and deterministic way

Question

Imagine two positive integers A and B. I want to combine these two into a single integer C.

There can be no other integers D and E which combine to C. So combining

Answer 1

How about something much simpler: Given two numbers, A and B let str be the concatenation: 'A' + ';' + 'B'. Then let the output be hash(str). I know that this is not a mathematical answer, but a simple python (which has an in built hash function) script should do the job.