Pyramid #462
Generating function
$$U_{462}(x, y) = \frac{\left(y + 1\right)^{4}}{9 \sqrt[3]{\frac{x}{2 \left(y + 1\right)^{2}} + \frac{\sqrt{3} \sqrt{x \left(27 x + 4 \left(y + 1\right)^{8}\right)}}{18 \left(y + 1\right)^{2}} + \frac{\left(y + 1\right)^{6}}{27}}} + \frac{\left(y + 1\right)^{2}}{3} + \sqrt[3]{\frac{x}{2 \left(y + 1\right)^{2}} + \frac{\sqrt{3} \sqrt{x \left(27 x + 4 \left(y + 1\right)^{8}\right)}}{18 \left(y + 1\right)^{2}} + \frac{\left(y + 1\right)^{6}}{27}}$$
Explicit formula
$$T_{462}(n, m, k) = \begin{cases}1&\text{if n=0 and m=0} ,\ \\\frac{2 k {\binom{2 k - 2 n - 1}{m - 1}}}{m}&\text{if m>0 and n=0} ,\ \\\frac{k {\binom{2 k - 8 n}{m}} {\binom{k - 2 n - 1}{n - 1}}}{n} \end{cases} $$
Data table
1 2 1 0 0 0 0
1 -6 21 -56 126 -252 462
-2 28 -21 112 -476 17136 -54264
7 -154 1771 -14168 8855 -46046 207207
-3 9 -1395 1488 -12276 834768 -486948
143 -5434 105963 -141284 1448161 -121645524 871792922
-728 33488 -786968 12591488 -154245728 154245728 -1311088688
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