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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 6240 |
| 4 | 64910 |
| 5 | 624128 |
| 6 | 3928640 |
| 7 | 21820160 |
| 8 | 102066525 |
| 9 | 435107840 |
| 10 | 1681228928 |
| 11 | 6065581440 |
| 12 | 20483625750 |
| 13 | 65651665920 |
| 14 | 200400925120 |
| 15 | 587021103104 |
| 16 | 1655255008870 |
| 17 | 4513857474560 |
| 18 | 11934605001600 |
| 19 | 30689664533440 |
| 20 | 76909902651384 |
| 21 | 188251191994880 |
| 22 | 450777531819200 |
[1,0,0,6240,64910,624128,3928640,21820160, 102066525,435107840,1681228928,6065581440, 20483625750,65651665920,200400925120,587021103104, 1655255008870,4513857474560,11934605001600, 30689664533440,76909902651384,188251191994880, 450777531819200] |