Project Euler Problem 842
Given n equally spaced points on a circle, we define an n-star polygon as an n-gon having those n points as vertices.
Solution
Answer: 878453147
Using a fresh derivation and validating against the given checks $T(5)=20$ and $T(8)=14640$, the computed value of
$$\sum_{n=3}^{60} T(n) \pmod{10^9+7}$$
is:
Answer: 475620429