$$U_{155}(x, y) = \frac{1 - \sqrt{- 4 x y^{3} - 12 x y^{2} - 12 x y - 4 x + 1}}{2 x \left(y + 1\right)^{3}}$$

$$T_{155}(n, m, k) = \frac{k {\binom{3 n}{m}} {\binom{k + 2 n}{n}}}{k + 2 n}$$