Pyramid #410
Generating function
$$U_{410}(x, y) = \frac{\sqrt{4 y + 1}}{4} + \frac{\sqrt{2 x \left(\sqrt{4 y + 1} + 1\right) + \frac{\left(\sqrt{4 y + 1} + 1\right)^{2}}{4}}}{2} + \frac{1}{4}$$
Explicit formula
$$T_{410}(n, m, k) = \begin{cases}1&\text{if n=0 and m=0} ,\ \\\frac{k {\binom{k - n - 1}{n - 1}}}{n}&\text{if m=0,n>0} ,\ \\\frac{\left(-1\right)^{m - 1} k {\binom{k - n}{n}} {\binom{- k + 2 m + n - 1}{m - 1}}}{m} \end{cases} $$
Data table
1 1 -1 2 -5 14 -42
1 0 0 0 0 0 0
-1 1 -2 5 -14 42 -132
2 -4 1 -28 84 -264 858
-5 15 -45 14 -45 1485 -5005
14 -56 196 -672 231 -8008 28028
-42 21 -84 315 -1155 42042 -15288
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