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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 6 |
| 5 | 18 |
| 6 | 19 |
| 7 | 27 |
| 8 | 57 |
| 9 | 249 |
| 10 | 396 |
| 11 | 7590 |
| 12 | 32715 |
| 13 | 70977 |
| 14 | 83586 |
[0,1,4,6,18,19,27,57,249,396,7590,32715,70977, 83586] |