$$U_{203}(x, y) = \frac{2 x - \sqrt{y \left(- 4 x^{2} - 4 x\right) + 1} + 1}{2 x^{2} + 2 x}$$

$$T_{203}(n, m, k) = \frac{k {\binom{k + n}{m}} {\binom{- k + 2 m - 1}{n}}}{k + n}$$