## Alexandrian Integers

### Problem 221

We shall call a positive integer `A` an "Alexandrian integer", if there exist integers `p`, `q`, `r` such that:

$$A = p \cdot q \cdot r$$ and $$\dfrac{1}{A} = \dfrac{1}{p} + \dfrac{1}{q} + \dfrac{1}{r}$$

For example, 630 is an Alexandrian integer ($p = 5, q = -7, r = -18$).
In fact, 630 is the 6^{th} Alexandrian integer, the first 6 Alexandrian integers being: 6, 42, 120, 156, 420, and 630.

Find the 150000^{th} Alexandrian integer.