Workshop 2: Math. Analysis - Why do we do proofs?

[@WendingWayfarer]

There's an easier proof: p + 1 must be even except where p is 2. Even implies one factor is 2. If one factor is 2, both must be two. This uniquely describes 4. 2 + 1 = 3, so p is not 2. This means p is uniquely 3.

[@JoelFeinstein]

I don't quite follow "If one factor is 2, both must be two." There are plenty of even squares which are not equal to 4. (For example 16, 36, ...)