Pyramid #586
Generating function
$$U_{586}(x, y) = \frac{\sqrt{\frac{32 \sqrt{3} x \sin^{3}{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{y}}{2} \right)}}{3} \right)}}{9 y^{\frac{3}{2}}} + \frac{4 \sin^{2}{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{y}}{2} \right)}}{3} \right)}}{3 y}}}{2} + \frac{\sqrt{3} \sin{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{y}}{2} \right)}}{3} \right)}}{3 \sqrt{y}}$$
Explicit formula
$$T_{586}(n, m, k) = \begin{cases}\frac{k {\binom{k + 3 m + n - 1}{m}}}{k + 2 m + n}&\text{if n==0} ,\ \\\frac{\left(-1\right)^{n - 1} k \left(k + n\right) {\binom{- k + 2 n - 1}{n - 1}} {\binom{k + 3 m + n - 1}{m}}}{n \left(k + 2 m + n\right)}&\text{if n>0} \end{cases} $$
Data table
1 1 3 12 55 273 1428
1 2 7 3 143 728 3876
-1 -3 -12 -55 -273 -1428 -7752
2 8 36 176 91 4896 27132
-5 -25 -125 -65 -35 -1938 -109725
14 84 462 2548 1428 81396 471086
-42 -294 -1764 -1029 -59976 -351918 -2082696
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