If you find any interesting numbers leave them here: for example, 47 has a lot of steps

Your 47 takes 104 steps. Interestingly enough, the number 107 takes exactly 100 steps. However, 97 takes a whopping 118 steps.

And 463 takes 128 steps, reaching as high as 9232 before coming down. The number 73 goes up to the same height, taking 115 steps. In fact, the others I had mentions (47, 97 and 107) all reach a maximum of 9232 -- curious.

@danpost the video in the description explains why. Two numbers steps may end up at the same result. for instance if you start at 10 you will get 10 -> 5 -> 16 -> 8 - > 4 -> 2 -> 1, and if you start at 21 you will get 21 -> 64 -> 32 -> 16 -> 8... and so on. Heres a small example: https://occupymath.files.wordpress.com/2017/04/collatz.png?w=700

You'll notice all of those numbers steps contain 107 as the first common number, so everything after 107 is all the same, and with that, you can take and number and, say you wanted to get 50 steps, find the (nSteps - 50)th number up there.

I can understand numbers closer to one being more commonly reached. However, a common high maximum for quite a few relatively small numbers was a bit surprising.

I guess it makes sense the the ones that take many steps would end up on along similar numbers as the many shorter paths take up most the other numbers.