MSG 148.18

\[\begin{align*} &E_{2}^{1,-1}=\mathbb{Z}\\ &E_{1}^{0,-1}=0\\ &E_{1}^{1,-1}=\mathbb{Z}[\boldsymbol{b}^{(1)}_{a_2}]\\ &E_{1}^{2,-1}=0 \end{align*}\]

\[\begin{align*} &[X^{(1)}]^{-1}=\left( \begin{array}{c} a_2 \\ 1 \\ \end{array} \right) \end{align*} \]