Pyramid #219
Generating function
$$U_{219}(x, y) = \frac{\left(y + 1\right) \left(- 2 x - \sqrt{1 - 4 x} + 1\right)}{2 x^{2}}$$
Explicit formula
$$T_{219}(n, m, k) = \frac{k {\binom{k}{m}} {\binom{2 k + 2 n}{n}}}{k + n}$$
Data table
1 1 0 0 0 0 0
2 2 0 0 0 0 0
5 5 0 0 0 0 0
14 14 0 0 0 0 0
42 42 0 0 0 0 0
132 132 0 0 0 0 0
429 429 0 0 0 0 0
Export
expand_less