$$U_{93}(x, y) = \frac{- 2 x - 2 y - \sqrt{- 4 x - 4 y + 1} + 1}{2 x + 2 y}$$

$$T_{93}(n, m, k) = \begin{cases}0&\text{if n=0,m=0} ,\ \\\frac{k {\binom{m + n}{m}} {\binom{2 m + 2 n}{- k + m + n}}}{m + n} \end{cases} $$