\[\sum_{\begin{subarray}{c}\pi\subseteq B(r,r,r)\\
\pi\mbox{\scriptsize\ descending plane partition}\end{subarray}}q^{|\pi|}=%
\prod_{1\leq h<j\leq r}\frac{1-q^{r+h+j-1}}{1-q^{2h+j-1}}.\]