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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 16 |
| 4 | 91 |
| 5 | 658 |
| 6 | 5567 |
| 7 | 54917 |
| 8 | 620081 |
| 9 | 7905592 |
| 10 | 112382245 |
| 11 | 1762646331 |
| 12 | 30231516786 |
| 13 | 562750751610 |
| 14 | 11297034281595 |
| 15 | 243241826522376 |
| 16 | 5591075279423398 |
| 17 | 136633359995403580 |
| 18 | 3537193288612096901 |
| 19 | 96697587673174195740 |
| 20 | 2783492094736121087958 |
[1,1,3,16,91,658,5567,54917,620081,7905592, 112382245,1762646331,30231516786,562750751610, 11297034281595,243241826522376,5591075279423398, 136633359995403580,3537193288612096901, 96697587673174195740,2783492094736121087958] |