$$U_{945}(x, y) = \frac{\left(x + y\right)^{2}}{1 - x}$$

$$T_{945}(n, m, k) = \begin{cases}{\binom{2 k}{m}} {\binom{- k + m + n - 1}{- 2 k + m + n}},\ \\0&\text{if n+m<2*k} \end{cases} $$