$$U_{1306}(x, y) = \frac{2 y^{3} \left(- \frac{x \left(1 - \sqrt{1 - 4 y}\right)}{y} - \sqrt{- \frac{2 x \left(1 - \sqrt{1 - 4 y}\right)}{y} + 1} + 1\right)^{2}}{x^{4} \left(1 - \sqrt{1 - 4 y}\right)^{3}}$$

$$T_{1306}(n, m, k) = \frac{2 k \left(k + n\right) {\binom{4 k + 2 n}{n}} {\binom{k + 2 m + n - 1}{m}}}{\left(2 k + n\right) \left(k + m + n\right)}$$