Pyramid #66
Generating function
$$U_{66}(x, y) = \frac{1 - \sqrt{1 - 4 y}}{x \sqrt{1 - 4 y} - x + 2 y}$$
Explicit formula
$$T_{66}(n, m, k) = \frac{k {\binom{k + n}{n}} {\binom{k + 2 m + n - 1}{m}}}{k + m + n}$$
Data table
1 1 2 5 14 42 132
1 2 5 14 42 132 429
1 3 9 28 9 297 1001
1 4 14 48 165 572 2002
1 5 2 75 275 1001 364
1 6 27 11 429 1638 6188
1 7 35 154 637 2548 9996
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