$$U_{1355}(x, y) = \frac{2 \sqrt{3} \sin{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{\frac{x}{\left(1 - 4 y\right)^{3}}}}{2} \right)}}{3} \right)}}{3 \sqrt{\frac{x}{\left(1 - 4 y\right)^{3}}} \left(1 - 4 y\right)^{\frac{3}{2}}}$$

$$T_{1355}(n, m, k) = \frac{4^{m} k {\binom{k + 3 n - 1}{n}} {\binom{\frac{3 k}{2} + m + 3 n - 1}{m}}}{k + 2 n}$$