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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 512 |
| 3 | 0 |
| 4 | 47872 |
| 5 | 92160 |
| 6 | 2671104 |
| 7 | 9246720 |
| 8 | 88632832 |
| 9 | 300627968 |
| 10 | 1708766720 |
| 11 | 5099440128 |
| 12 | 21224886528 |
| 13 | 55690063872 |
| 14 | 187789235712 |
| 15 | 440993452032 |
| 16 | 1275935628288 |
| 17 | 2731242852352 |
| 18 | 7030806944256 |
| 19 | 13931439616000 |
[1,0,512,0,47872,92160,2671104,9246720,88632832, 300627968,1708766720,5099440128,21224886528, 55690063872,187789235712,440993452032, 1275935628288,2731242852352,7030806944256, 13931439616000] |