or the reverse, where a repeating expansion in a variable base to be rational? been trying some trial and error cases without success
by variable base we mean each digit can be in a different base but any digit can occur as many times in the same base or not
Just in case anybody tries to pull a fast one no base $\sqrt 2$, $\pi$ , $e$ etc. can not have the irrational number itself as base, that would make this trivial.