Pyramid #1144
Pyramid #1145
Pyramid #1146
Generating function
$$U_{1145}(x, y) = \frac{1}{\left(- x \left(y + 1\right)^{3} + 1\right)^{3}}$$
Explicit formula
$$T_{1145}(n, m, k) = {\binom{3 n}{m}} {\binom{3 k + n - 1}{n}}$$
Data table
1 0 0 0 0 0 0
3 9 9 3 0 0 0
6 36 9 12 9 36 6
1 9 36 84 126 126 84
15 18 99 33 7425 1188 1386
21 315 2205 9555 28665 63063 105105
28 504 4284 22848 8568 239904 519792
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