Generating function
$$U_{1469}(x, y) = \frac{2 \sqrt{3} \left(y + 1\right)^{2} \sin{\left(\frac{\arcsin{\left(\frac{3 \sqrt{3} \sqrt{x \left(y + 1\right)^{3}}}{2} \right)}}{3} \right)}}{3 \sqrt{x \left(y + 1\right)}}$$
Explicit formula
$$T_{1469}(n, m, k) = \frac{k {\binom{3 k + 3 n}{m}} {\binom{k + 3 n - 1}{n}}}{k + 2 n}$$
Data table
1 3 3 1 0 0 0
1 6 15 2 15 6 1
3 27 108 252 378 378 252
12 144 792 264 594 9504 11088
55 825 5775 25025 75075 165165 275275
273 4914 41769 222768 83538 2339064 5067972
1428 29988 29988 189924 854658 29058372 77488992
Export
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