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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 8 |
| 4 | 75 |
| 5 | 904 |
| 6 | 13255 |
| 7 | 229536 |
| 8 | 4587961 |
| 9 | 103971680 |
| 10 | 2634212961 |
| 11 | 73787255200 |
| 12 | 2264440519891 |
| 13 | 75563445303072 |
| 14 | 2724356214102055 |
| 15 | 105546202276277504 |
| 16 | 4373078169296869425 |
| 17 | 192970687573630633216 |
| 18 | 9035613818754820178689 |
| 19 | 447469496697658409400960 |
[1,0,1,8,75,904,13255,229536,4587961,103971680, 2634212961,73787255200,2264440519891, 75563445303072,2724356214102055, 105546202276277504,4373078169296869425, 192970687573630633216,9035613818754820178689, 447469496697658409400960] |