Generating function
$$U_{1478}(x, y) = \frac{2 \sqrt{3} \sin{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{x}}{2} \right)}}{3} \right)}}{3 \sqrt{x} \left(1 - y\right)^{3}}$$
Explicit formula
$$T_{1478}(n, m, k) = \frac{k {\binom{k + 3 n - 1}{n}} {\binom{3 k + m - 1}{m}}}{k + 2 n}$$
Data table
1 3 6 1 15 21 28
1 3 6 1 15 21 28
3 9 18 3 45 63 84
12 36 72 12 18 252 336
55 165 33 55 825 1155 154
273 819 1638 273 4095 5733 7644
1428 4284 8568 1428 2142 29988 39984
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