$$U_{746}(x, y) = \frac{\left(1 - \sqrt{- 4 x \left(y + 1\right) + 1}\right)^{4}}{16 x^{4} \left(y + 1\right)^{3}}$$

$$T_{746}(n, m, k) = \frac{2 k {\binom{k + n}{m}} {\binom{4 k + 2 n}{n}}}{2 k + n}$$