I claim that all numbers and all sequences of numbers are computable, given enough time. So, what about a random number is not computable?

There is a common theme in computer science to say that True Random Numbers are not computable. This is wrong. All numbers are computable; their non-predictability is what makes them random, instead of pseudo-random.

What about the co-mingling of PRN and TRN data; how low a percentage mix of TRN makes otherwise PRN data non-predictable?