How to proof the randomness of a number sequence?

Question

I've got a sequence of numbers generator by a "random number generator". Is there a way or a method to proof the randomness of the generator?

How would I even compare randomness of generators?

Or might it be better to proof that a sequence is not random?

Answer 1

There are several random number tests, but it is impossible to prove that a sequence of numbers is in fact random.

Answer 2

The article by A. Kolmogorov and V. Uspenskii is a serious treatment of the topic.