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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 19 |
| 6 | 76 |
| 7 | 320 |
| 8 | 1469 |
| 9 | 7048 |
| 10 | 35233 |
| 11 | 181656 |
| 12 | 960800 |
| 13 | 5189579 |
[1,1,2,6,19,76,320,1469,7048,35233,181656,960800, 5189579] |