CAOP

$$\begin{align} Q_n(q^{-x};a,b,N|q) &= \sum_{k=0}^\infty \frac{(q^{-n};q)_k (abq^{n+1};q)_k (q^{-x};q)_k}{(aq;q)_k (q^{-N};q)_k (q;q)_k} q^k\\ &= {}_{3}\phi_{2}\!\left(\left. {q^{-n}, abq^{n+1}, q^{-x} \atop aq, q^{-N}} \; \right| q ; q \right) \end{align}$$