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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 9 |
| 5 | 33 |
| 6 | 185 |
| 7 | 1861 |
| 8 | 35285 |
| 9 | 845657 |
| 10 | 28275879 |
| 11 | 1543673839 |
| 12 | 135800422841 |
| 13 | 17596518150277 |
[1,1,1,9,33,185,1861,35285,845657,28275879, 1543673839,135800422841,17596518150277] |