$$U_{902}(x, y) = x \left(1 - y\right) + \frac{\sqrt{4 x + \frac{1}{\left(1 - y\right)^{4}}}}{2 \left(1 - y\right)} + \frac{1}{2 \left(1 - y\right)^{3}}$$

$$T_{902}(n, m, k) = \begin{cases}{\binom{3 k + m - 1}{m}}&\text{if n=0} ,\ \\\frac{2 \left(-1\right)^{n - 1} k {\binom{- 2 k + 2 n - 1}{n - 1}} {\binom{3 k + m - 4 n - 1}{m}}}{n} \end{cases} $$