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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 10 |
| 6 | 61 |
| 7 | 564 |
| 8 | 7593 |
| 9 | 123874 |
| 10 | 2262877 |
| 11 | 44190279 |
| 12 | 904777809 |
| 13 | 19207129217 |
[0,1,1,3,10,61,564,7593,123874,2262877,44190279, 904777809,19207129217] |