$$U_{770}(x, y) = \frac{2 \sqrt{3} \left(1 - \frac{4 \sin^{2}{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{- x}}{2} \right)}}{3} \right)}}{3}\right)^{2} \sin{\left(\frac{\arcsin{\left(\frac{3 \sqrt{3} \sqrt{y}}{2} \right)}}{3} \right)}}{3 \sqrt{y}}$$

$$TLeftA_{271825}(n, k) = \begin{cases}1&\text{if n = 0},\\\frac {k {(-1)}^{n-1}} {n} {\binom{3n-k-1}{n-1}} &\text{if n > 0},\\\end{cases} $$$$T_{770}(n, m, k) = \frac{k \operatorname{TLeftA_{271825}}{\left(n,2 k \right)} {\binom{k + 3 m - 1}{m}}}{k + 2 m}$$