Hehe I asked because time ago I implemented something similar (using console though) and by instinct I was doing the same, coloring numbers based on divisors to see patterns, and primes, but just when I wanted to get some conclusion out that, I had to stop and do something else, so it kinda remained in my brain as something I had to finish to consciously understand.

Thanks for explaining then, so what we did is a Sieve of Eratosthenes... But I have to admit that I also coded it to see which particular patterns (if any) primes were drawing on screen.. :)