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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 52 |
| 4 | 451 |
| 5 | 3498 |
| 6 | 23502 |
| 7 | 173611 |
| 8 | 1323447 |
| 9 | 9920654 |
| 10 | 73573634 |
| 11 | 545170514 |
| 12 | 4060213800 |
| 13 | 30266880736 |
| 14 | 225316532881 |
| 15 | 1676398961171 |
| 16 | 12475867876511 |
| 17 | 92870049802057 |
| 18 | 691310371544378 |
| 19 | 5145544200921776 |
| 20 | 38298595223058076 |
| 21 | 285066094324142481 |
| 22 | 2121840794371117780 |
[1,1,5,52,451,3498,23502,173611,1323447,9920654, 73573634,545170514,4060213800,30266880736, 225316532881,1676398961171,12475867876511, 92870049802057,691310371544378,5145544200921776, 38298595223058076,285066094324142481, 2121840794371117780] |