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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 8 |
| 6 | 13 |
| 7 | 36 |
| 8 | 76 |
| 9 | 202 |
| 10 | 482 |
| 11 | 1281 |
| 12 | 3277 |
| 13 | 8749 |
| 14 | 23083 |
| 15 | 62056 |
| 16 | 166498 |
| 17 | 450576 |
| 18 | 1220542 |
| 19 | 3321870 |
| 20 | 9057388 |
| 21 | 24769906 |
[1,1,2,3,8,13,36,76,202,482,1281,3277,8749,23083, 62056,166498,450576,1220542,3321870,9057388, 24769906] |