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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 6 |
| 6 | 26 |
| 7 | 122 |
| 8 | 1015 |
| 9 | 11847 |
| 10 | 208914 |
| 11 | 5236991 |
| 12 | 184321511 |
[1,1,1,3,6,26,122,1015,11847,208914,5236991, 184321511] |