\begin{align}
     &\mathcal{C} = \mathcal{A} \times_{(j_{m_1}, j_{m_2}, \dots j_{m_S})}^{(i_{n1}, i_{n2}, \dots i_{n_S})} \mathcal{B}  \notag
\\&
    = \sum_{i_{1},i_{2},\cdots i_{N}} \mathcal{A}_{i_1,i_2,\cdots i_{n_S},*}\quad\mathcal{B}_{*,i_1,i_2,\cdots i_{n_S}}.\notag
\end{align}
