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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
| 6 | 7 |
| 7 | 14 |
| 8 | 35 |
| 9 | 84 |
| 10 | 249 |
| 11 | 801 |
| 12 | 2977 |
| 13 | 12965 |
| 14 | 59937 |
| 15 | 313230 |
| 16 | 1701935 |
[0,0,1,2,4,7,14,35,84,249,801,2977,12965,59937, 313230,1701935] |