Generating function
$$U_{1122}(x, y) = \left(\frac{x}{\left(1 - y\right)^{2}} + 1\right)^{3}$$
Explicit formula
$$T_{1122}(n, m, k) = {\binom{3 k}{n}} {\binom{m + 2 n - 1}{m}}$$
Data table
1 0 0 0 0 0 0
3 6 9 12 15 18 21
3 12 3 6 105 168 252
1 6 21 56 126 252 462
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
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