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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 23 |
| 6 | 58 |
| 7 | 134 |
| 8 | 308 |
| 9 | 677 |
| 10 | 1470 |
| 11 | 3106 |
| 12 | 6479 |
| 13 | 13260 |
| 14 | 26827 |
| 15 | 53516 |
[0,1,3,9,23,58,134,308,677,1470,3106,6479,13260, 26827,53516] |