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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 9 |
| 8 | 21 |
| 9 | 61 |
| 10 | 255 |
| 11 | 1001 |
| 12 | 4645 |
| 13 | 25381 |
| 14 | 168687 |
| 15 | 1415389 |
[1,1,1,1,1,1,9,21,61,255,1001,4645,25381,168687, 1415389] |