Pyramid #903
Generating function
$$U_{903}(x, y) = \frac{\sqrt{- 4 x y^{2} - 8 x y - 4 x + 1} + 1}{2 y + 2}$$
Explicit formula
$$T_{903}(n, m, k) = \begin{cases}1&\text{if n=0, m=0} ,\ \\2&\text{if 2*n-k=0, m=0} ,\ \\0&\text{if 2*n-k=0, m>0} ,\ \\- \frac{k {\binom{- k + 2 n}{m}} {\binom{- k + 2 n}{n}}}{- k + 2 n} \end{cases} $$
Data table
1 -1 1 -1 1 -1 1
-1 -1 0 0 0 0 0
-1 -3 -3 -1 0 0 0
-2 -1 -2 -2 -1 -2 0
-5 -35 -105 -175 -175 -105 -35
-14 -126 -504 -1176 -1764 -1764 -1176
-42 -462 -231 -693 -1386 -19404 -19404
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