Pyramid #425
Generating function
$$U_{425}(x, y) = \frac{2 x y - x + \sqrt{x^{2} - 4 x y + 2 x + 1} - 1}{2 y - 2}$$
Explicit formula
$$T_{425}(n, m, k) = \begin{cases}0&\text{if n<2*k or m=0} ,\ \\- \frac{\left(-1\right)^{m - 1} k {\binom{- k + n - 1}{m - 1}} {\binom{k - m - 1}{n}}}{m} \end{cases} $$
Data table
0 0 0 0 0 0 0
0 0 0 0 0 0 0
0 -1 0 0 0 0 0
0 1 -2 0 0 0 0
0 -1 5 -5 0 0 0
0 1 -9 21 -14 0 0
0 -1 14 -56 84 -42 0
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