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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 4 |
| 5 | 18 |
| 6 | 107 |
| 7 | 846 |
| 8 | 11122 |
| 9 | 261212 |
| 10 | 11717906 |
| 11 | 1006716728 |
| 12 | 164060156360 |
| 13 | 50335920919080 |
| 14 | 29003488522658695 |
| 15 | 31397381311096116107 |
| 16 | 63969560164236980493127 |
| 17 | 245871831711291931225960094 |
| 18 | 1787331725280413408599670721723 |
| 19 | 24636021429463963332562215579906526 |
[0,0,1,4,18,107,846,11122,261212,11717906, 1006716728,164060156360,50335920919080, 29003488522658695,31397381311096116107, 63969560164236980493127, 245871831711291931225960094, 1787331725280413408599670721723, 24636021429463963332562215579906526] |