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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 16 |
| 5 | 200 |
| 6 | 2400 |
| 7 | 29400 |
| 8 | 376320 |
| 9 | 5080320 |
| 10 | 72576000 |
| 11 | 1097712000 |
| 12 | 17563392000 |
| 13 | 296821324800 |
| 14 | 5288816332800 |
| 15 | 99165306240000 |
| 16 | 1952793722880000 |
| 17 | 40311241850880000 |
| 18 | 870722823979008000 |
| 19 | 19645683716026368000 |
| 20 | 462251381553561600000 |
| 21 | 11325158848062259200000 |
[0,0,0,1,16,200,2400,29400,376320,5080320, 72576000,1097712000,17563392000,296821324800, 5288816332800,99165306240000,1952793722880000, 40311241850880000,870722823979008000, 19645683716026368000,462251381553561600000, 11325158848062259200000] |