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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 23 |
| 4 | 230 |
| 5 | 1682 |
| 6 | 23548 |
| 7 | 259723 |
| 8 | 4675014 |
| 9 | 69413294 |
| 10 | 1527092468 |
| 11 | 28588019814 |
| 12 | 743288515164 |
| 13 | 16818059163492 |
| 14 | 504541774904760 |
| 15 | 13397724585164019 |
| 16 | 455522635895576646 |
| 17 | 13892023109165902550 |
| 18 | 527896878148304296900 |
[1,1,6,23,230,1682,23548,259723,4675014,69413294, 1527092468,28588019814,743288515164, 16818059163492,504541774904760,13397724585164019, 455522635895576646,13892023109165902550, 527896878148304296900] |