Well, I got the answer....
However, I also believe I have a secondary solution that met the conditions of the challenge just fine, except not as efficient.
After setting MAX to 10 billion for testing, the accepted solution took ~15 seconds to iterate while another one-line solution still solved the problem, however it took the same iteration ~40 seconds to complete.
Perhaps the mission should state something about efficiency?
Mind you, I guess all programmers strive for efficiency so....
Cool, learned something new today
Am I allowed to post the one-line solution I found that doesn't solve this mission (but still solves it) to drum up some conversation?