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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 3 |
| 6 | 8 |
| 7 | 22 |
| 8 | 71 |
| 9 | 93 |
| 10 | 638 |
| 11 | 9144 |
| 12 | 26821 |
| 13 | 2373690 |
| 14 | 11013191 |
| 15 | 950468551 |
| 16 | 23819080360 |
| 17 | 4860600739719 |
| 18 | 18887557655957 |
| 19 | 23748158395676 |
| 20 | 102452785866447 |
| 21 | 1153981434332852712 |
| 22 | 722919835385951370578 |
[1,1,1,2,3,8,22,71,93,638,9144,26821,2373690, 11013191,950468551,23819080360,4860600739719, 18887557655957,23748158395676,102452785866447, 1153981434332852712,722919835385951370578] |