$$U_{289}(x, y) = - \frac{2 \sin{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{y}}{2} \right)}}{3} \right)}}{2 x \sin{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{y}}{2} \right)}}{3} \right)} - \sqrt{3} \sqrt{y}}$$

$$T_{289}(n, m, k) = \frac{k {\binom{k + n}{n}} {\binom{k + 3 m + n - 1}{m}}}{k + 2 m + n}$$