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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 8 |
| 5 | 47 |
| 6 | 266 |
| 7 | 1339 |
| 8 | 6544 |
| 9 | 29837 |
| 10 | 133495 |
| 11 | 585002 |
| 12 | 2542563 |
| 13 | 10959656 |
[0,0,1,8,47,266,1339,6544,29837,133495,585002, 2542563,10959656] |