Pyramid #124
Generating function
$$U_{124}(x, y) = \frac{x - \sqrt{x^{2} - 2 x + y \left(4 x - 4\right) + 1} - 1}{2 x - 2}$$
Explicit formula
$$T_{124}(n, m, k) = \begin{cases}1&\text{if n=0, m=0} ,\ \\0&\text{if m=0} ,\ \\- \frac{k {\binom{- k + 2 m - 1}{m - 1}} {\binom{m + n - 1}{n}}}{m}&\text{if m>0} \end{cases} $$
Data table
1 -1 -1 -2 -5 -14 -42
0 -1 -2 -6 -2 -7 -252
0 -1 -3 -12 -5 -21 -882
0 -1 -4 -2 -1 -49 -2352
0 -1 -5 -3 -175 -98 -5292
0 -1 -6 -42 -28 -1764 -10584
0 -1 -7 -56 -42 -294 -19404
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