I'm confused by the idea of a Wilson Prime. The theorem states that $$p^2=(p-1)!+1$$
This makes sense for $5$: $$5^2=(4\times3\times2)+1$$ so $5^2=25$
But it makes no sense to me for $13$: $$13^2=4790016001$$ Clearly I am as far from a mathematician as possible. If you can help in very simple terms...