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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 1 |
| 7 | 4 |
| 8 | 41 |
| 9 | 1981 |
| 10 | 304496 |
| 11 | 78322916 |
| 12 | 27033154065 |
| 13 | 11934777413049 |
| 14 | 6593485023089912 |
| 15 | 4485517185017734885 |
| 16 | 3707462300996644966161 |
| 17 | 3680029088808704302571244 |
| 18 | 4341813441626431900011624077 |
| 19 | 6033239205199253768404631967656 |
| 20 | 9792722283774379198364367866020815 |
[0,0,0,0,1,1,4,41,1981,304496,78322916, 27033154065,11934777413049,6593485023089912, 4485517185017734885,3707462300996644966161, 3680029088808704302571244, 4341813441626431900011624077, 6033239205199253768404631967656, 9792722283774379198364367866020815] |