$$U_{1304}(x, y) = \frac{\left(1 - y\right)^{6} \left(- \frac{2 x}{\left(1 - y\right)^{2}} - \sqrt{- \frac{4 x}{\left(1 - y\right)^{2}} + 1} + 1\right)^{2}}{4 x^{4}}$$

$$T_{1304}(n, m, k) = \frac{2 k {\binom{4 k + 2 n}{n}} {\binom{2 k + m + 2 n - 1}{m}}}{2 k + n}$$