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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 0 |
| 3 | 4 |
| 4 | 24 |
| 5 | 256 |
| 6 | 3360 |
| 7 | 53824 |
| 8 | 1016064 |
| 9 | 22095616 |
| 10 | 543966720 |
| 11 | 14955833344 |
| 12 | 454227400704 |
| 13 | 15103031627776 |
| 14 | 545668238868480 |
| 15 | 21286707282264064 |
| 16 | 891735287528914944 |
| 17 | 39926103010743156736 |
[0,1,0,4,24,256,3360,53824,1016064,22095616, 543966720,14955833344,454227400704,15103031627776, 545668238868480,21286707282264064, 891735287528914944,39926103010743156736] |