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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 4 |
| 6 | 326 |
| 7 | 628 |
| 8 | 992 |
| 9 | 98304 |
| 10 | 125568 |
| 11 | 733440 |
| 12 | 281163264 |
| 13 | 386427322368 |
| 14 | 3178249003008 |
| 15 | 12454223855616 |
| 16 | 6450728943845376 |
| 17 | 342348724735967232 |
| 18 | 20218431581110665216 |
| 19 | 39814891891080560640 |
| 20 | 82739188294287768944640 |
| 21 | 15336676441718784000 |
| 22 | 61298453882755419734016000 |
[0,0,1,1,4,326,628,992,98304,125568,733440, 281163264,386427322368,3178249003008, 12454223855616,6450728943845376, 342348724735967232,20218431581110665216, 39814891891080560640,82739188294287768944640, 15336676441718784000,61298453882755419734016000] |