Generating function
$$U_{471}(x, y) = \frac{\sqrt{4 y + 1}}{6} + \frac{\left(\sqrt{4 y + 1} + 1\right)^{2}}{36 \sqrt[3]{\frac{x}{\sqrt{4 y + 1} + 1} + \frac{\sqrt{3} \sqrt{x \left(27 x + \frac{\left(\sqrt{4 y + 1} + 1\right)^{4}}{4}\right)}}{9 \sqrt{4 y + 1} + 9} + \frac{\left(\sqrt{4 y + 1} + 1\right)^{3}}{216}}} + \sqrt[3]{\frac{x}{\sqrt{4 y + 1} + 1} + \frac{\sqrt{3} \sqrt{x \left(27 x + \frac{\left(\sqrt{4 y + 1} + 1\right)^{4}}{4}\right)}}{9 \sqrt{4 y + 1} + 9} + \frac{\left(\sqrt{4 y + 1} + 1\right)^{3}}{216}} + \frac{1}{6}$$
Explicit formula
$$T_{471}(n, m, k) = \begin{cases}1&\text{if n=0 and m=0} ,\ \\\frac{\left(-1\right)^{n - 1} k {\binom{- k + 3 n - 1}{n - 1}}}{n}&\text{if m=0} ,\ \\\frac{\left(-1\right)^{m - 1} k {\binom{- k + 2 m + n - 1}{m - 1}}}{m}&\text{if n=0} ,\ \\\frac{\left(-1\right)^{m - 1} k \left(k - 4 n\right) {\binom{k - 2 n - 1}{n - 1}} {\binom{- k + 2 m + 4 n - 1}{m - 1}}}{m n}&\text{if n>0 and m>0} \end{cases} $$
| 1 | 1 | -1 | 2 | -5 | 14 | -42 |
| 1 | -3 | 9 | -28 | 9 | -297 | 1001 |
| -2 | 14 | -7 | 308 | -1274 | 5096 | -19992 |
| 7 | -77 | 539 | -308 | 15708 | -74613 | 337953 |
| -3 | 45 | -405 | 285 | -17325 | 95634 | -49335 |
| 143 | -2717 | 29887 | -249964 | 176605 | -11126115 | 64531467 |
| -728 | 16744 | -217672 | 2109744 | -1699516 | 120422848 | -776519744 |
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