Solution: Powerful Integers

Statement

Given three integers x, y, and bound, return a list of all powerful integers whose value is less than or equal to bound.

An integer is considered powerful if it can be expressed as x$^i$ + y$^j$ for some non negative integers $i$ and $j$ (i.e., $i \geq 0$ and $j \geq 0$).

The result may be returned in any order, and each value should appear at most once in the output. ...