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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 12 |
| 4 | 24 |
| 5 | 60 |
| 6 | 180 |
| 7 | 588 |
| 8 | 1968 |
| 9 | 6840 |
| 10 | 24240 |
| 11 | 87252 |
| 12 | 318360 |
| 13 | 1173744 |
| 14 | 4366740 |
| 15 | 16370700 |
| 16 | 61780320 |
| 17 | 234505140 |
| 18 | 894692736 |
| 19 | 3429028116 |
| 20 | 13195862760 |
| 21 | 50968206912 |
| 22 | 197517813636 |
| 23 | 767766750564 |
| 24 | 2992650987408 |
| 25 | 11694675166500 |
| 26 | 45807740881032 |
[1,0,0,12,24,60,180,588,1968,6840,24240,87252, 318360,1173744,4366740,16370700,61780320, 234505140,894692736,3429028116,13195862760, 50968206912,197517813636,767766750564, 2992650987408,11694675166500,45807740881032] |