$$U_{64}(x, y) = \frac{- x + \sqrt{x^{2} + 2 y \sqrt{1 - 4 x} + y \left(4 x - 2\right)}}{y \left(\sqrt{1 - 4 x} - 1\right)}$$

$$T_{64}(n, m, k) = \frac{k {\binom{k + 2 m}{m}} {\binom{k + 2 m + 2 n - 1}{n}}}{k + 2 m + n}$$