$$U_{1048}(x, y) = \frac{\left(1 - \sqrt{1 - 4 y}\right)^{3}}{8 y^{3} \left(1 - x\right)^{3}}$$

$$T_{1048}(n, m, k) = \frac{3 k {\binom{3 k + 2 m - 1}{m}} {\binom{3 k + n - 1}{n}}}{3 k + m}$$