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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 12 |
| 5 | 120 |
| 6 | 2460 |
| 7 | 64680 |
| 8 | 2323692 |
| 9 | 111920760 |
| 10 | 7272700860 |
| 11 | 639739653960 |
| 12 | 76764606923532 |
| 13 | 12645557866982040 |
| 14 | 2878366780307114460 |
| 15 | 909775941009828296040 |
| 16 | 401039212596034472197932 |
| 17 | 247339947733328456032703160 |
| 18 | 214013123181627427780427544060 |
[0,0,0,0,12,120,2460,64680,2323692,111920760, 7272700860,639739653960,76764606923532, 12645557866982040,2878366780307114460, 909775941009828296040,401039212596034472197932, 247339947733328456032703160, 214013123181627427780427544060] |