Q: "What do you mean by describe?"

A: Literally describe any commonality between the elements of P. This commonality should be universal and can be best described in words (so you don't even have to use math!). Make sure to give proof of your claim though (this part should be math).

Also, if you can't give a complete description, give us some important information about these elements and why: are they all positive? are they all even numbers? etc...

(~suffering_in_progress)