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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 9 |
| 5 | 37 |
| 6 | 207 |
| 7 | 1192 |
| 8 | 11449 |
| 9 | 93673 |
| 10 | 892783 |
| 11 | 8534308 |
| 12 | 148561283 |
| 13 | 1740198891 |
[1,1,1,2,9,37,207,1192,11449,93673,892783,8534308, 148561283,1740198891] |