\[H_{n}\left(\cos\theta\,|\,q\right)=\sum_{\ell=0}^{n}\frac{\left(q;q\right)_{n}%
{\mathrm{e}}^{\mathrm{i}(n-2\ell)\theta}}{\left(q;q\right)_{\ell}\left(q;q%
\right)_{n-\ell}}={\mathrm{e}}^{\mathrm{i}n\theta}{{}_{2}\phi_{0}}\left({q^{-n%
},0\atop-};q,q^{n}{\mathrm{e}}^{-2\mathrm{i}\theta}\right).\]