$$U_{802}(x, y) = \frac{- 2 x + y - \sqrt{4 x + y^{2} + y \left(- 4 x - 2\right) + 1} - 1}{2 y - 2}$$

$$T_{802}(n, m, k) = \begin{cases}\frac{2 \left(-1\right)^{n - 1} k {\binom{- 2 k + 2 n - 1}{n - 1}} {\binom{m + n - 1}{m}}}{n}&\text{if n>0} ,\ \\0&\text{if n=0} \end{cases} $$