$$U_{1098}(x, y) = \frac{\left(1 - \sqrt{1 - 4 y}\right)^{3} \left(- 2 x - \sqrt{1 - 4 x} + 1\right)^{3}}{64 x^{6} y^{3}}$$

$$T_{1098}(n, m, k) = \frac{9 k^{2} {\binom{6 k + 2 n}{n}} {\binom{3 k + 2 m - 1}{m}}}{\left(3 k + m\right) \left(3 k + n\right)}$$