Hmmm... all right, just remember: patent pendin! And I thought of it first! I'll sue you!
[math]\big_{n=2}^\infty gn[/math] (this is 'a') where g is every positive prime integer, beginning with 2, 3, 5, 7, 11, and 13. You do not find prime numbers, but nonprime numbers! And then [math]\big_{n=2}^\infty n^n'[/math](this is 'b') Where n' is every number beginning with 2, irrelevant to what n is. So, the set of all positive integers minus the set of {a+b}, that is to say, the numbers found in the solution of a and b.