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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 48 |
| 4 | 384 |
| 5 | 1920 |
| 6 | 46080 |
| 7 | 645120 |
| 8 | 5160960 |
| 9 | 185794560 |
| 10 | 530841600 |
| 11 | 40874803200 |
| 12 | 280284364800 |
| 13 | 51011754393600 |
| 14 | 714164561510400 |
| 15 | 42849873690624000 |
| 16 | 1371195958099968000 |
| 17 | 302731575164928000 |
| 18 | 1678343852714360832000 |
| 19 | 100120983364435968000 |
| 20 | 1275541328062914232320000 |
[1,2,4,48,384,1920,46080,645120,5160960,185794560, 530841600,40874803200,280284364800,51011754393600, 714164561510400,42849873690624000, 1371195958099968000,302731575164928000, 1678343852714360832000,100120983364435968000, 1275541328062914232320000] |