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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 15 |
| 6 | 51 |
| 7 | 190 |
| 8 | 765 |
| 9 | 3226 |
| 10 | 14131 |
| 11 | 63007 |
| 12 | 285772 |
| 13 | 995837 |
| 14 | 6061703 |
[1,1,2,6,15,51,190,765,3226,14131,63007,285772, 995837,6061703] |