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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 9 |
| 6 | 26 |
| 7 | 80 |
| 8 | 340 |
| 9 | 1690 |
| 10 | 11432 |
| 11 | 101142 |
| 12 | 1228608 |
| 13 | 20329150 |
[1,1,2,6,9,26,80,340,1690,11432,101142,1228608, 20329150] |