Generating function
$$U_{1040}(x, y) = \frac{y + 1}{\left(1 - x\right)^{3}}$$
Explicit formula
$$T_{1040}(n, m, k) = {\binom{k}{m}} {\binom{3 k + n - 1}{n}}$$
Data table
1 1 0 0 0 0 0
3 3 0 0 0 0 0
6 6 0 0 0 0 0
1 1 0 0 0 0 0
15 15 0 0 0 0 0
21 21 0 0 0 0 0
28 28 0 0 0 0 0
Export
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