Pyramid #943
Generating function
$$U_{943}(x, y) = \left(x + 1\right) \left(x + y\right)^{3}$$
Explicit formula
$$T_{943}(n, m, k) = {\binom{k}{- 3 k + m + n}} {\binom{3 k}{m}}$$
Data table
0 0 0 1 0 0 0
0 0 3 1 0 0 0
0 3 3 0 0 0 0
1 3 0 0 0 0 0
1 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
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