Pyramid #379
Generating function
$$U_{379}(x, y) = \sqrt[3]{\frac{x \sqrt{1 - 4 y}}{2} + \frac{\sqrt{3} \sqrt{x \left(27 x + \frac{4}{\left(1 - 4 y\right)^{2}}\right)} \sqrt{1 - 4 y}}{18} + \frac{1}{27 \left(1 - 4 y\right)^{\frac{3}{2}}}} + \frac{1}{\left(9 - 36 y\right) \sqrt[3]{\frac{x \sqrt{1 - 4 y}}{2} + \frac{\sqrt{3} \sqrt{x \left(27 x + \frac{4}{\left(1 - 4 y\right)^{2}}\right)} \sqrt{1 - 4 y}}{18} + \frac{1}{27 \left(1 - 4 y\right)^{\frac{3}{2}}}}} + \frac{1}{3 \sqrt{1 - 4 y}}$$
Explicit formula
$$T_{379}(n, m, k) = \begin{cases}1&\text{if n=0 and m=0} ,\ \\\frac{\left(-1\right)^{m - 1} \cdot 4^{m} k {\binom{- \frac{k}{2} + \frac{3 n}{2} - 1}{m - 1}}}{2 m}&\text{if n=0 and m>0} ,\ \\\frac{\left(-1\right)^{n - 1} \cdot 4^{m} k {\binom{- k + 3 n - 1}{n - 1}} {\binom{\frac{k}{2} + m - 2 n - 1}{m}}}{n}&\text{if n>0} \end{cases} $$
Data table
1 2 4 32/3 32 512/5 1024/3
1 -4 0 0 0 0 0
-2 24 -96 128 0 0 0
7 -14 112 -448 896 -7168 0
-3 84 -1008 672 -2688 64512 -86016
143 -5148 82368 -768768 4612608 -18450432 49201152
-728 32032 -64064 768768 -6150144 344408064 -1377632256
Export
expand_less