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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 20 |
| 7 | 48 |
| 8 | 115 |
| 9 | 286 |
| 10 | 719 |
| 11 | 1838 |
| 12 | 4734 |
| 13 | 12247 |
| 14 | 31617 |
| 15 | 81208 |
[1,1,2,4,9,20,48,115,286,719,1838,4734,12247, 31617,81208] |