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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 9 |
| 3 | 24 |
| 4 | 60 |
| 5 | 141 |
| 6 | 328 |
| 7 | 738 |
| 8 | 1647 |
| 9 | 3618 |
| 10 | 7893 |
| 11 | 17055 |
| 12 | 36619 |
| 13 | 78144 |
| 14 | 165888 |
| 15 | 350619 |
| 16 | 738012 |
| 17 | 1548279 |
| 18 | 3237611 |
| 19 | 6752439 |
| 20 | 14046525 |
| 21 | 29157612 |
| 22 | 60396996 |
| 23 | 124885167 |
[1,3,9,24,60,141,328,738,1647,3618,7893,17055, 36619,78144,165888,350619,738012,1548279,3237611, 6752439,14046525,29157612,60396996,124885167] |