$$U_{75}(x, y) = \frac{\sqrt{y \left(4 x^{2} - 8 x + 4\right) + 1} + 1}{2 x^{2} - 4 x + 2}$$

$$T_{75}(n, m, k) = \begin{cases}n + 1&\text{if m=0} ,\ \\\frac{k {\binom{k - m - 1}{m - 1}} {\binom{2 k - 2 m + n - 1}{n}}}{m} \end{cases} $$