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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 33 |
| 4 | 550 |
| 5 | 21280 |
| 6 | 1625205 |
| 7 | 295884064 |
| 8 | 121507526212 |
| 9 | 109033312482811 |
| 10 | 221192898468933365 |
| 11 | 1004038485574289617464 |
[1,6,33,550,21280,1625205,295884064,121507526212, 109033312482811,221192898468933365, 1004038485574289617464] |