Absolute stability region
Stable region in red.

Coefficients

\begin{align} \begin{array}{c|ccccc} & & & & & \\ \frac{1}{2} & \frac{1}{2} & & & & \\ \frac{1}{4} & \frac{1}{4} & & & & \\ \frac{1}{2} & & & \frac{1}{2} & & \\ \frac{3}{4} & \frac{1}{4} & & & \frac{1}{2} & \\ \hline & & - \frac{1}{3} & \frac{2}{3} & & \frac{2}{3}\\ & & & \frac{1}{2} & & \frac{1}{2} \end{array}\end{align}

Properties