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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 32 |
| 6 | 130 |
| 7 | 622 |
| 8 | 3839 |
| 9 | 28614 |
| 10 | 258660 |
| 11 | 2799801 |
| 12 | 36537753 |
| 13 | 580312616 |
[1,2,4,11,32,130,622,3839,28614,258660,2799801, 36537753,580312616] |