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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 43 |
| 4 | 334 |
| 5 | 2717 |
| 6 | 22776 |
| 7 | 195000 |
| 8 | 1695874 |
| 9 | 14927990 |
| 10 | 132673398 |
| 11 | 1188412986 |
| 12 | 10714602196 |
| 13 | 97133633788 |
| 14 | 884716464592 |
| 15 | 8091061578807 |
| 16 | 74259516900390 |
| 17 | 683694381314696 |
| 18 | 6312247839166260 |
| 19 | 58424001667319720 |
| 20 | 541971167468786770 |
[1,1,6,43,334,2717,22776,195000,1695874,14927990, 132673398,1188412986,10714602196,97133633788, 884716464592,8091061578807,74259516900390, 683694381314696,6312247839166260, 58424001667319720,541971167468786770] |