Generating function
$$U_{1475}(x, y) = \frac{2 \sqrt{3} \sin{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{\frac{x}{\left(1 - y\right)^{3}}}}{2} \right)}}{3} \right)}}{3 \sqrt{\frac{x}{1 - y}}}$$
Explicit formula
$$T_{1475}(n, m, k) = \frac{k {\binom{k + 3 n - 1}{n}} {\binom{k + m + 3 n - 1}{m}}}{k + 2 n}$$
Data table
1 1 1 1 1 1 1
1 4 1 2 35 56 84
3 21 84 252 63 1386 2772
12 12 66 264 858 24024 6006
55 715 5005 25025 1001 34034 102102
273 4368 37128 222768 1058148 4232592 14814072
1428 27132 27132 189924 1044582 48050772 192203088
Export
expand_less