$$U_{26}(x, y) = \frac{1 - \sqrt{y \left(- 4 x^{3} - 8 x^{2} - 4 x\right) + 1}}{x y \left(2 x + 2\right)}$$

$$T_{26}(n, m, k) = \frac{k {\binom{k + 2 m}{m}} {\binom{k + 2 m}{- m + n}}}{k + 2 m}$$