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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 10 |
| 5 | 23 |
| 6 | 66 |
| 7 | 189 |
| 8 | 574 |
| 9 | 1773 |
| 10 | 5640 |
| 11 | 18208 |
| 12 | 59774 |
| 13 | 198654 |
[1,1,2,4,10,23,66,189,574,1773,5640,18208,59774, 198654] |