A man attempts to prove (by hand) the Collatz Conjecture which states that you can pick any whole number and repeatedly half it if it is even, or multiply it by three and add one if it is odd and you will eventually get *the number one*.

Since this requires a lot of work, the man is never available to spend time with his friends. For this reason his friends eventually stop attempting to hang out with him since he will almost assuredly be working on the Collatz Conjecture and thus will not be able to join them in their activities.