Periodic function:
$ x[n]=e^{j2\pi n} $
$ {x[n] = 2\pi/2\pi = 1} $
It's rational because one is an integer so it's periodic!!!!
Non Periodic function:
$ x[n]=e^{j2\pi*\pi n} $
$ {x[n] = 2\pi*\pi/2\pi = \pi} $
It's not periodic $ {\pi} $ is irrational.
