Pyramid #523
Generating function
$$U_{523}(x, y) = - \frac{1}{\left(1 - y\right)^{3} \left(x - \frac{1}{\left(1 - y\right)^{2}}\right)}$$
Explicit formula
$$T_{523}(n, m, k) = {\binom{k + n - 1}{n}} {\binom{k + m - 2 n - 1}{m}}$$
Data table
1 1 1 1 1 1 1
1 -1 0 0 0 0 0
1 -3 3 -1 0 0 0
1 -5 1 -1 5 -1 0
1 -7 21 -35 35 -21 7
1 -9 36 -84 126 -126 84
1 -11 55 -165 33 -462 462
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