$$U_{662}(x, y) = - \frac{1}{\sqrt{1 - 4 y} \left(\frac{x}{1 - 4 y} - 1\right)}$$

$$T_{662}(n, m, k) = 4^{m} {\binom{k + n - 1}{n}} {\binom{\frac{k}{2} + m + n - 1}{m}}$$