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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 9 |
| 4 | 68 |
| 5 | 732 |
| 6 | 10250 |
| 7 | 176654 |
| 8 | 3613044 |
| 9 | 85476720 |
| 10 | 2295275372 |
| 11 | 68949496421 |
| 12 | 2290588299708 |
| 13 | 83374406924240 |
| 14 | 3299390271801838 |
| 15 | 141034101443780374 |
| 16 | 6475752407825487220 |
| 17 | 317866884692663325892 |
| 18 | 16609896989101220207880 |
[1,1,2,9,68,732,10250,176654,3613044,85476720, 2295275372,68949496421,2290588299708, 83374406924240,3299390271801838, 141034101443780374,6475752407825487220, 317866884692663325892,16609896989101220207880] |