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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 0 |
| 6 | 0 |
| 7 | 0 |
| 8 | 0 |
| 9 | 0 |
| 10 | 0 |
| 11 | 0 |
| 12 | 1 |
| 13 | 4 |
| 14 | 20 |
| 15 | 120 |
| 16 | 836 |
| 17 | 6700 |
| 18 | 60360 |
| 19 | 603960 |
| 20 | 6646090 |
| 21 | 79773180 |
| 22 | 1037232420 |
| 23 | 14523065760 |
| 24 | 217865924620 |
| 25 | 3486094113460 |
| 26 | 59266711626080 |
| 27 | 1066844378466720 |
| 28 | 20270696788641635 |
| 29 | 405424394055173080 |
| 30 | 8514090075293512920 |
[0,0,0,0,0,0,0,0,0,0,0,0,1,4,20,120,836,6700, 60360,603960,6646090,79773180,1037232420, 14523065760,217865924620,3486094113460, 59266711626080,1066844378466720,20270696788641635, 405424394055173080,8514090075293512920] |