$$U_{611}(x, y) = \frac{\sqrt{1 - 4 y} \left(- \sqrt{4 x + \frac{1}{\left(1 - 4 y\right)^{2}}} + \frac{1}{1 - 4 y}\right)}{2}$$

$$T_{611}(n, m, k) = \begin{cases}0&\text{if n < k} ,\ \\- \frac{4^{m} k {\binom{k - n - 1}{n - 1}} {\binom{\frac{k}{2} + m - 2 n - 1}{m}}}{n} \end{cases} $$