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| n | a(n) |
|---|---|
| 3 | 0 |
| 4 | 6 |
| 5 | 60 |
| 6 | 500 |
| 7 | 3640 |
| 8 | 25410 |
| 9 | 172620 |
| 10 | 1164492 |
| 11 | 7850304 |
| 12 | 53178972 |
| 13 | 362810448 |
| 14 | 2495592528 |
| 15 | 17313238800 |
| 16 | 121098656250 |
[0,6,60,500,3640,25410,172620,1164492,7850304, 53178972,362810448,2495592528,17313238800, 121098656250] |