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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 8 |
| 6 | 40 |
| 7 | 160 |
| 8 | 576 |
| 9 | 1920 |
| 10 | 6528 |
| 11 | 23040 |
| 12 | 84480 |
| 13 | 317440 |
| 14 | 1198080 |
| 15 | 4508328 |
| 16 | 16908288 |
| 17 | 63406080 |
| 18 | 238605640 |
| 19 | 902430720 |
| 20 | 3429236736 |
| 21 | 13076616480 |
| 22 | 49977753600 |
| 23 | 191312691200 |
| 24 | 733365665600 |
| 25 | 2815436626328 |
| 26 | 10825959997440 |
| 27 | 41694904974720 |
| 28 | 160823204904960 |
[0,0,0,0,8,40,160,576,1920,6528,23040,84480, 317440,1198080,4508328,16908288,63406080, 238605640,902430720,3429236736,13076616480, 49977753600,191312691200,733365665600, 2815436626328,10825959997440,41694904974720, 160823204904960] |