Pyramid #268
Generating function
$$U_{268}(x, y) = \frac{x}{2} + \frac{y}{2} + \frac{\sqrt{x^{2} + 2 x + y^{2} + y \left(2 - 2 x\right) + 1}}{2} + \frac{1}{2}$$
Explicit formula
$$T_{268}(n, m, k) = \begin{cases}{\binom{k}{n}}&\text{if m=0} ,\ \\\frac{\left(-1\right)^{m - 1} {\binom{k - m - 1}{n}} {\binom{- k + m + n - 1}{m - 1}}}{m} \end{cases} $$
Data table
1 1 0 0 0 0 0
1 -1 1 -1 1 -1 1
0 1 -3 6 -1 15 -21
0 -1 6 -2 5 -105 196
0 1 -1 5 -175 49 -1176
0 -1 15 -105 49 -1764 5292
0 1 -21 196 -1176 5292 -19404
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