$$U_{96}(x, y) = \frac{x + y}{\sqrt[3]{- 9 x - 9 y + 1}}$$

$$T_{96}(n, m, k) = 9^{- k + m + n} {\binom{m + n}{m}} {\binom{- \frac{2 k}{3} + m + n - 1}{- k + m + n}}$$