What is a periodic pattern in 1D cellular automata?
I have this 3-color, code 1599 rule and I can see that a certain generation can be grouped together by their similar or foreseeable pattern, then it becomes complex and back to similar or foreseeable pattern and finally to just the same pattern over and over again. But is it not some mathematical way to find out if it's periodic, something more then just "looks like some periods do have the same pattern"?