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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 24 |
| 5 | 144 |
| 6 | 1398 |
| 7 | 11184 |
| 8 | 97200 |
| 9 | 973296 |
| 10 | 10950696 |
| 11 | 131408352 |
| 12 | 1593191808 |
| 13 | 22304685312 |
| 14 | 333297226080 |
| 15 | 5103130001760 |
| 16 | 81686161277280 |
| 17 | 1470350902991040 |
| 18 | 26490792085668288 |
| 19 | 529815841713365760 |
| 20 | 10635027891469974720 |
[0,0,0,24,144,1398,11184,97200,973296,10950696, 131408352,1593191808,22304685312,333297226080, 5103130001760,81686161277280,1470350902991040, 26490792085668288,529815841713365760, 10635027891469974720] |