Problem #WSP-000348

Problems Number Theory Divisibility

Problem

A robot is programmed to move along the number line starting at 2. At each second, the number by which it moves up by must be a factor of the number it’s currently on, but not 1. For example, if the robot gets to 10, then it can move forward by 2, 5 or 10 steps, going to 12, 15, or 20. What numbers can it land on, and what numbers can’t it land on?