$$U_{1126}(x, y) = \left(\frac{x \left(1 - \sqrt{1 - 4 y}\right)^{3}}{8 y^{3}} + 1\right)^{3}$$

$$T_{1126}(n, m, k) = \frac{3 n {\binom{3 k}{n}} {\binom{2 m + 3 n - 1}{m}}}{m + 3 n}$$