$$U_{1325}(x, y) = \frac{- x - 2 y - \sqrt{x^{2} - 2 x - 4 y + 1} + 1}{2 x y + 2 y^{2}}$$

$$T_{1325}(n, m, k) = \frac{k {\binom{2 k + 2 m + n}{m}} {\binom{k + m + n - 1}{n}}}{k + m}$$