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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 49 |
| 5 | 161 |
| 6 | 656 |
| 7 | 2751 |
| 8 | 12505 |
| 9 | 58482 |
| 10 | 280348 |
| 11 | 1374563 |
| 12 | 6864809 |
[1,4,13,49,161,656,2751,12505,58482,280348, 1374563,6864809] |