Pyramid #676
Pyramid #677
Pyramid #678
Generating function
$$U_{677}(x, y) = \frac{x \left(1 - \sqrt{1 - 4 y}\right)}{2 y} + 1$$
Explicit formula
$$T_{677}(n, m, k) = \frac{n {\binom{k}{n}} {\binom{2 m + n - 1}{m}}}{m + n}$$
Data table
nan 0 0 0 0 0 0
1 1 2 5 14 42 132
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 0 0 0 0 0 0
Related
Pyramid #701: Right on x
Pyramid #678: Left on x
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