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| n | a(n) |
|---|---|
| 6 | 1 |
| 7 | 0 |
| 8 | 2 |
| 9 | 1 |
| 10 | 6 |
| 11 | 6 |
| 12 | 28 |
| 13 | 53 |
| 14 | 229 |
| 15 | 712 |
| 16 | 3336 |
| 17 | 15099 |
| 18 | 82419 |
| 19 | 477584 |
| 20 | 3086563 |
| 21 | 21566457 |
| 22 | 164113460 |
| 23 | 1350167015 |
| 24 | 12007072739 |
| 25 | 115165535180 |
[1,0,2,1,6,6,28,53,229,712,3336,15099,82419, 477584,3086563,21566457,164113460,1350167015, 12007072739,115165535180] |