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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 42 |
| 5 | 255 |
| 6 | 1785 |
| 7 | 14406 |
| 8 | 131236 |
| 9 | 1328037 |
| 10 | 14809965 |
| 11 | 180014054 |
| 12 | 2371072374 |
| 13 | 33607312219 |
| 14 | 510183508471 |
| 15 | 8255546409722 |
| 16 | 141855645636152 |
| 17 | 2579236008913689 |
| 18 | 49471832899923129 |
| 19 | 998261936044450726 |
| 20 | 21138674688880283370 |
| 21 | 468687157358947546415 |
| 22 | 10858634384569444410179 |
[1,1,2,9,42,255,1785,14406,131236,1328037, 14809965,180014054,2371072374,33607312219, 510183508471,8255546409722,141855645636152, 2579236008913689,49471832899923129, 998261936044450726,21138674688880283370, 468687157358947546415,10858634384569444410179] |