$$U_{264}(x, y) = \frac{\sqrt{1 - 4 x} - \sqrt{- 4 x - 4 y \sqrt{1 - 4 x} + 1}}{2 y \sqrt{1 - 4 x}}$$

$$T_{264}(n, m, k) = \begin{cases}\frac{k {\binom{k + 2 m - 1}{m}} {\binom{\frac{k}{2} + \frac{m}{2} + n - \frac{1}{2}}{n}} {\binom{k + m + 2 n - 1}{\frac{k}{2} + \frac{m}{2} + n - \frac{1}{2}}}}{\left(k + m\right) {\binom{k + m - 1}{\frac{k}{2} + \frac{m}{2} - \frac{1}{2}}}}&\text{if k odd} ,\ \\\frac{k {\binom{\frac{k}{2} + \frac{m}{2} + n}{n}} {\binom{k + m + 2 n}{\frac{k}{2} + \frac{m}{2} + n}} {\binom{k + 2 m - 1}{m}}}{\left(k + m\right) {\binom{k + m}{\frac{k}{2} + \frac{m}{2}}}}&\text{if k even} \end{cases} $$