1 problem

Let $q$ be a formal variable, let $m_1,m_2,m_3,m_4\geq 0$, and define $\theta(a_1,\ldots,a_r;Q)=\prod_{i=1}^r(a_i;Q)_\infty(Q/a_i;Q)_\infty$. Nandi's identity. The following multis…