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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 6 |
| 3 | 120 |
| 4 | 1980 |
| 5 | 32970 |
| 6 | 584430 |
| 7 | 11204676 |
| 8 | 233098740 |
| 9 | 5254404210 |
| 10 | 127921380840 |
| 11 | 3350718545460 |
| 12 | 94062457204716 |
| 13 | 2819367702529560 |
| 14 | 89912640142178490 |
| 15 | 3040986592542420060 |
| 16 | 108752084073199561140 |
| 17 | 4101112025363285051526 |
[0,0,6,120,1980,32970,584430,11204676,233098740, 5254404210,127921380840,3350718545460, 94062457204716,2819367702529560,89912640142178490, 3040986592542420060,108752084073199561140, 4101112025363285051526] |