$$U_{983}(x, y) = \frac{\sqrt{4 x \left(y + 1\right) + 1} + 1}{2 \left(y + 1\right)^{2}}$$

$$T_{983}(n, m, k) = \begin{cases}\frac{\left(-1\right)^{n - 1} k {\binom{- 2 k + n}{m}} {\binom{- k + 2 n - 1}{n - 1}}}{n}&\text{if n>0} ,\ \\{\binom{- 2 k + n}{m}}&\text{if n==0} \end{cases} $$