Beraha constants

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

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

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

The following table summarizes the first ten Beraha constants.

• Chromatic polynomial

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