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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 24 |
| 4 | 112 |
| 5 | 504 |
| 6 | 2528 |
| 7 | 11712 |
| 8 | 52160 |
| 9 | 230048 |
| 10 | 1000320 |
| 11 | 4294016 |
| 12 | 18264832 |
| 13 | 77098880 |
| 14 | 323290624 |
| 15 | 1347997696 |
| 16 | 5593390080 |
| 17 | 23110676992 |
| 18 | 95130810368 |
| 19 | 390287108096 |
| 20 | 1596449140736 |
| 21 | 6512744568832 |
| 22 | 26504685772800 |
| 23 | 107628465111040 |
[0,0,24,112,504,2528,11712,52160,230048,1000320, 4294016,18264832,77098880,323290624,1347997696, 5593390080,23110676992,95130810368,390287108096, 1596449140736,6512744568832,26504685772800, 107628465111040] |