Pyramid #1445
Pyramid #1446
Pyramid #1447
Generating function
$$U_{1446}(x, y) = \frac{\left(y + 1\right)^{2}}{\left(- x \left(y + 1\right)^{3} + 1\right)^{3}}$$
Explicit formula
$$T_{1446}(n, m, k) = {\binom{2 k + 3 n}{m}} {\binom{3 k + n - 1}{n}}$$
Data table
1 2 1 0 0 0 0
3 15 3 3 15 3 0
6 48 168 336 42 336 168
1 11 55 165 33 462 462
15 21 1365 546 15015 3003 45045
21 357 2856 1428 4998 129948 259896
28 56 532 3192 13566 434112 108528
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