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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 40 |
| 4 | 267 |
| 5 | 1897 |
| 6 | 14123 |
| 7 | 108719 |
| 8 | 858421 |
| 9 | 6913914 |
| 10 | 56583401 |
| 11 | 469200322 |
| 12 | 3933669482 |
| 13 | 33287843079 |
| 14 | 283956543780 |
| 15 | 2439153154289 |
| 16 | 21080183230758 |
| 17 | 183168147509467 |
| 18 | 1599221574473345 |
| 19 | 14022758576502463 |
| 20 | 123435372854088656 |
| 21 | 1090356552158960402 |
[1,1,7,40,267,1897,14123,108719,858421,6913914, 56583401,469200322,3933669482,33287843079, 283956543780,2439153154289,21080183230758, 183168147509467,1599221574473345, 14022758576502463,123435372854088656, 1090356552158960402] |