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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 0 |
| 3 | 0 |
| 4 | 8 |
| 5 | 24 |
| 6 | 0 |
| 7 | 216 |
| 8 | 4608 |
| 9 | 20736 |
| 10 | 0 |
| 11 | 1267200 |
| 12 | 30067200 |
| 13 | 194918400 |
| 14 | 0 |
| 15 | 27840153600 |
| 16 | 855119462400 |
| 17 | 7276643942400 |
| 18 | 0 |
| 19 | 1869882900480000 |
| 20 | 71740296069120000 |
| 21 | 754326563880960000 |
| 22 | 0 |
| 23 | 303064905515581440000 |
| 24 | 14020774294498836480000 |
| 25 | 175480402397791518720000 |
| 26 | 0 |
[1,0,0,8,24,0,216,4608,20736,0,1267200,30067200, 194918400,0,27840153600,855119462400, 7276643942400,0,1869882900480000, 71740296069120000,754326563880960000,0, 303064905515581440000,14020774294498836480000, 175480402397791518720000,0] |