$$U_{299}(x, y) = \frac{1 - \sqrt{- 4 x y^{3} - 12 x y^{2} - 12 x y - 4 x + 1}}{2 x y + 2 x}$$

$$T_{299}(n, m, k) = \begin{cases}1&\text{if n=0 and m=0} ,\ \\\frac{k {\binom{2 k + 3 n}{m}} {\binom{k + 2 n - 1}{n}}}{k + n} \end{cases} $$