$$U_{791}(x, y) = \frac{3 x \left(- \sqrt{1 - \frac{y \left(8 - 8 \cos{\left(\frac{2 \arcsin{\left(\frac{3 \sqrt{3} \sqrt{x}}{2} \right)}}{3} \right)}\right)}{3 x}} + 1 - \frac{y \left(4 - 4 \cos{\left(\frac{2 \arcsin{\left(\frac{3 \sqrt{3} \sqrt{x}}{2} \right)}}{3} \right)}\right)}{3 x}\right)}{y^{2} \left(4 - 4 \cos{\left(\frac{2 \arcsin{\left(\frac{3 \sqrt{3} \sqrt{x}}{2} \right)}}{3} \right)}\right)}$$

$$T_{791}(n, m, k) = \frac{k {\binom{2 k + 2 m}{m}} {\binom{2 k + 2 m + 3 n - 1}{n}}}{k + m + n}$$