How to list undergraduate paper on CV Mathematics.
Not novel research ~ merely an analysis / reformulation of an existing, proved theorem
Not a thesis, but was a major (50%) component of a senior course.
Never published.
The math isn't even advanced - it's actually quite basic - but it's fun!


(a) Should I even mention this on a CV?

(b) If I should, how would I go about doing so? How to site it? Host and provide link?
The paper alone isn't worthy of your CV. It's not a peer-reviewed publication, which is about the closest place it would fit. You could list the senior project under your education section to provide an idea of your area of focus, but the paper alone doesn't carry any weight. I had a senior capstone project in my undergraduate curriculum, and I have listed the project as sort of my undergraduate "thesis", but not referring to any text.