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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 15 |
| 3 | 267 |
| 4 | 9450 |
| 5 | 577785 |
| 6 | 58537749 |
| 7 | 9751519234 |
| 8 | 2673230750387 |
| 9 | 1220300742842014 |
[1,2,15,267,9450,577785,58537749,9751519234, 2673230750387,1220300742842014] |