Pyramid #107
Generating function
$$U_{107}(x, y) = \frac{x - 1}{x + y - 1}$$
Explicit formula
$$T_{107}(n, m, k) = \begin{cases}1&\text{if n=0 and m=0} ,\ \\\frac{k {\binom{m + n}{m}} {\binom{k + m - 1}{k}}}{m + n} \end{cases} $$
Data table
1 1 1 1 1 1 1
0 1 2 3 4 5 6
0 1 3 6 1 15 21
0 1 4 1 2 35 56
0 1 5 15 35 7 126
0 1 6 21 56 126 252
0 1 7 28 84 21 462
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