Pyramid #565
Generating function
$$U_{565}(x, y) = \frac{1 - \frac{4 \sin^{2}{\left(\frac{\operatorname{asin}{\left(\frac{3 \sqrt{3} \sqrt{- x}}{2} \right)}}{3} \right)}}{3}}{\left(1 - y\right)^{2}}$$
Explicit formula
$$T_{565}(n, m, k) = \begin{cases}{\binom{2 k + m - 1}{m}}&\text{if n==0} ,\ \\\frac{\left(-1\right)^{n - 1} k {\binom{- k + 3 n - 1}{n - 1}} {\binom{2 k + m - 1}{m}}}{n}&\text{if n>0} \end{cases} $$
Data table
1 2 3 4 5 6 7
1 2 3 4 5 6 7
-2 -4 -6 -8 -1 -12 -14
7 14 21 28 35 42 49
-3 -6 -9 -12 -15 -18 -21
143 286 429 572 715 858 1001
-728 -1456 -2184 -2912 -364 -4368 -5096
Export
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