Absolute stability region
Stable region in red.

Coefficients

\begin{align} \begin{array}{c|cccccccccccccccc} & & & & & & & & & & & & & & & & \\ \frac{1}{2} & \frac{1}{2} & & & & & & & & & & & & & & & \\ \frac{1}{3} & \frac{1}{3} & & & & & & & & & & & & & & & \\ \frac{2}{3} & \frac{1}{3} & & \frac{1}{3} & & & & & & & & & & & & & \\ \frac{1}{4} & \frac{1}{4} & & & & & & & & & & & & & & & \\ \frac{1}{2} & \frac{1}{4} & & & & \frac{1}{4} & & & & & & & & & & & \\ \frac{3}{4} & \frac{1}{4} & & & & \frac{1}{4} & \frac{1}{4} & & & & & & & & & & \\ \frac{1}{5} & \frac{1}{5} & & & & & & & & & & & & & & & \\ \frac{2}{5} & \frac{1}{5} & & & & & & & \frac{1}{5} & & & & & & & & \\ \frac{3}{5} & \frac{1}{5} & & & & & & & \frac{1}{5} & \frac{1}{5} & & & & & & & \\ \frac{4}{5} & \frac{1}{5} & & & & & & & \frac{1}{5} & \frac{1}{5} & \frac{1}{5} & & & & & & \\ \frac{1}{6} & \frac{1}{6} & & & & & & & & & & & & & & & \\ \frac{1}{3} & \frac{1}{6} & & & & & & & & & & & \frac{1}{6} & & & & \\ \frac{1}{2} & \frac{1}{6} & & & & & & & & & & & \frac{1}{6} & \frac{1}{6} & & & \\ \frac{2}{3} & \frac{1}{6} & & & & & & & & & & & \frac{1}{6} & \frac{1}{6} & \frac{1}{6} & & \\ \frac{5}{6} & \frac{1}{6} & & & & & & & & & & & \frac{1}{6} & \frac{1}{6} & \frac{1}{6} & \frac{1}{6} & \\ \hline & & \frac{2}{3} & - \frac{27}{4} & - \frac{27}{4} & \frac{64}{3} & \frac{64}{3} & \frac{64}{3} & - \frac{625}{24} & - \frac{625}{24} & - \frac{625}{24} & - \frac{625}{24} & \frac{54}{5} & \frac{54}{5} & \frac{54}{5} & \frac{54}{5} & \frac{54}{5}\\ & & \frac{1}{3} & - \frac{9}{2} & - \frac{9}{2} & 16 & 16 & 16 & - \frac{125}{6} & - \frac{125}{6} & - \frac{125}{6} & - \frac{125}{6} & 9 & 9 & 9 & 9 & 9 \end{array}\end{align}

Properties