green flage
basically 3x+1 is like this, pick a number, if it's odd, multiply by 3 and the add 1. if it's even, then divide by 2. MOst likely, every NATURAL number will end up with the loop of 4 to 2 to 1 and back to 4. people are still seeing if any numbers don't follow that pattern, and possibly make a different pattern.
