$$U_{787}(x, y) = \frac{8 \sqrt{3} \left(y + 1\right)^{2} \sin^{3}{\left(\frac{\arcsin{\left(\frac{3 \sqrt{3} \sqrt{x}}{2} \right)}}{3} \right)}}{9 x^{\frac{3}{2}}}$$

$$T_{787}(n, m, k) = \frac{3 k {\binom{2 k}{m}} {\binom{3 k + 3 n - 1}{n}}}{3 k + 2 n}$$