I was trying to calculate something and at some point I get the following sum:
\begin{equation} \sum_{t=0,t \text{ even}}^{s}{s+3n \brack s-t}\sum_{i = 0}^{t/2}q^{2i^2}{t/2+2n-i \brack t/2-i}{n \brack 2i}x^t \end{equation} can it be simplified by using a $q$-binomial identity?