$$U_{954}(x, y) = \frac{1}{1 - \left(x + y\right)^{2}}$$

$$T_{954}(n, m, k) = \begin{cases}{\binom{m + n}{m}} {\binom{k + \frac{m}{2} + \frac{n}{2} - 1}{\frac{m}{2} + \frac{n}{2}}}&\text{if n + m even} ,\ \\0 \end{cases} $$