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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 6 |
| 5 | 0 |
| 6 | 90 |
| 7 | 180 |
| 8 | 90 |
| 9 | 1680 |
| 10 | 5040 |
| 11 | 5040 |
| 12 | 36330 |
| 13 | 138600 |
| 14 | 207900 |
| 15 | 895356 |
| 16 | 3818430 |
| 17 | 7567560 |
| 18 | 24720696 |
| 19 | 106702596 |
| 20 | 258053796 |
| 21 | 742135680 |
| 22 | 3050807760 |
| 23 | 8483450976 |
| 24 | 23450218506 |
| 25 | 89691647760 |
| 26 | 273414861720 |
| 27 | 760735601340 |
| 28 | 2713845780360 |
| 29 | 8733512193120 |
| 30 | 24957399366900 |
[1,0,0,6,6,0,90,180,90,1680,5040,5040,36330, 138600,207900,895356,3818430,7567560,24720696, 106702596,258053796,742135680,3050807760, 8483450976,23450218506,89691647760,273414861720, 760735601340,2713845780360,8733512193120, 24957399366900] |