Absolute stability region
Stable region in red.

Coefficients

\begin{align} \begin{array}{c|ccccc} & & & & & \\ \frac{1}{3} & \frac{1}{3} & & & & \\ \frac{1}{3} & \frac{1}{6} & \frac{1}{6} & & & \\ \frac{1}{2} & \frac{1}{8} & & \frac{3}{8} & & \\ 1 & \frac{1}{2} & & - \frac{3}{2} & 2 & \\ \hline & \frac{1}{6} & & & \frac{2}{3} & \frac{1}{6}\\ & \frac{1}{10} & & \frac{3}{10} & \frac{2}{5} & \frac{1}{5} \end{array}\end{align}

Properties