Beraha constants

The Beraha constants are a series of mathematical constants by which the $$n\text{th}$$ Beraha constant is given by


 * $$B (n) = 2 + 2 \cos \left ( \frac{2\pi}{n} \right ).$$

Notable examples of Beraha constants include $$B (5)$$is $$\varphi + 1$$, where $$\varphi$$ is the golden ratio, $$B (7)$$is the silver constant (also known as the silver root), and $$B (10) = \varphi + 2$$.

The following table summarizes the first ten Beraha constants.