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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 8 |
| 3 | 57 |
| 4 | 439 |
| 5 | 3443 |
| 6 | 27301 |
| 7 | 218451 |
| 8 | 1761801 |
| 9 | 14308236 |
| 10 | 116924574 |
| 11 | 960792743 |
| 12 | 7934362761 |
| 13 | 65817379234 |
| 14 | 548190108992 |
| 15 | 4582721143115 |
| 16 | 38439422184737 |
| 17 | 323420836565182 |
| 18 | 2728901670629808 |
| 19 | 23085534477376835 |
| 20 | 195766417450435773 |
| 21 | 1663818353085104919 |
[1,2,8,57,439,3443,27301,218451,1761801,14308236, 116924574,960792743,7934362761,65817379234, 548190108992,4582721143115,38439422184737, 323420836565182,2728901670629808, 23085534477376835,195766417450435773, 1663818353085104919] |