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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 33 |
| 6 | 152 |
| 7 | 1006 |
| 8 | 11805 |
| 9 | 257542 |
| 10 | 11011758 |
| 11 | 917095022 |
| 12 | 145164791300 |
[1,2,4,11,33,152,1006,11805,257542,11011758, 917095022,145164791300] |