$$U_{79}(x, y) = \frac{x^{2}}{2} + x + \frac{\left(x + 1\right) \sqrt{x^{2} + 2 x + 4 y + 1}}{2} + \frac{1}{2}$$

$$T_{79}(n, m, k) = \begin{cases}1&\text{if n=0 and m=0} ,\ \\\frac{\left(-1\right)^{m - 1} k {\binom{- k + 2 m - 1}{m - 1}}}{m}&\text{if n=0 and m>0} ,\ \\\frac{2 k {\binom{k - m}{m}} {\binom{2 k - 2 m - 1}{n - 1}}}{n}&\text{if n>0} \end{cases} $$