$$U_{387}(x, y) = \frac{- y \left(2 x + 2\right) - \sqrt{y \left(- 4 x - 4\right) + 1} + 1}{y^{2} \left(2 x + 2\right)}$$

$$T_{387}(n, m, k) = \frac{k {\binom{k + m}{n}} {\binom{2 k + 2 m}{m}}}{k + m}$$