Pyramid #824
Generating function
$$U_{824}(x, y) = \frac{- 4 \sqrt{3} x \sqrt{y} \sin{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{y}}{2} \right)}}{3} \right)} + 3 y - \sqrt{- 24 \sqrt{3} x y^{\frac{3}{2}} \sin{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{y}}{2} \right)}}{3} \right)} + 9 y^{2}}}{8 x^{2} \sin^{2}{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{y}}{2} \right)}}{3} \right)}}$$
Explicit formula
$$T_{824}(n, m, k) = \begin{cases}1&\text{if n=0,m=0} ,\ \\\frac{k n {\binom{2 k + 2 n}{n}} {\binom{3 m + n - 1}{m}}}{\left(k + n\right) \left(2 m + n\right)} \end{cases} $$
Data table
1 0 0 0 0 0 0
2 2 6 24 11 546 2856
5 1 35 15 715 364 1938
14 42 168 77 3822 19992 108528
42 168 756 3696 1911 102816 569772
132 66 33 1716 924 511632 289674
429 2574 14157 78078 43758 2494206 14435421
Export
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