Pyramid #457
Generating function
$$U_{457}(x, y) = \frac{1}{\frac{4 y \sin^{2}{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{- x}}{2} \right)}}{3} \right)}}{3} - y + 1}$$
Explicit formula
$$T_{457}(n, m, k) = \begin{cases}{\binom{k + m - 1}{m}}&\text{if n=0} ,\ \\\frac{\left(-1\right)^{n - 1} m {\binom{k + m - 1}{m}} {\binom{- m + 3 n - 1}{n - 1}}}{n} \end{cases} $$
Data table
1 1 1 1 1 1 1
0 1 2 3 4 5 6
0 -2 -3 -3 -2 0 3
0 7 1 1 8 5 2
0 -3 -42 -42 -35 -25 -15
0 143 198 198 168 126 84
0 -728 -1001 -1001 -858 -66 -462
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