$$U_{115}(x, y) = \frac{2}{- 2 x + y^{2} + \left(y + 1\right) \sqrt{- 4 x + y^{2} - 2 y + 1} + 1}$$

$$T_{115}(n, m, k) = \begin{cases}1&\text{if n=0 and m=0} ,\ \\\frac{2 k {\binom{m + n}{n}} {\binom{2 k + m + 2 n - 1}{n - 1}}}{m + n} \end{cases} $$