$$U_{744}(x, y) = \frac{\left(y + 1\right)^{2}}{\left(- x \left(y + 1\right)^{2} + 1\right)^{3}}$$

$$T_{744}(n, m, k) = \frac{3 k {\binom{2 k + 2 n}{m}} {\binom{3 k + n}{n}}}{3 k + n}$$