$$U_{220}(x, y) = \frac{- 2 x - \sqrt{1 - 4 x} + 1}{2 x^{2} + y \left(2 x + \sqrt{1 - 4 x} - 1\right)}$$

$$T_{220}(n, m, k) = \frac{k {\binom{k + m}{m}} {\binom{2 k + 2 m + 2 n}{n}}}{k + m + n}$$