$F_6$
$${\rm LOG}\left(F_6\right)=\frac{1}{3}\pi
\left[\begin{array}{rrrrrr}
\bullet & \bullet & \bullet & \bullet & \bullet & \bullet\\
\bullet & 1 & 2 & 3 & 4 & 5\\
\bullet & 2 & 4 & \bullet & 2 & 4\\
\bullet & 3 & \bullet & 3 & \bullet & 3\\
\bullet & 4 & 2 & \bullet & 4 & 2\\
\bullet & 5 & 4 & 3 & 2 & 1
\end{array}\right]$$