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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 24 |
| 3 | 216 |
| 4 | 1824 |
| 5 | 15150 |
| 6 | 124416 |
| 7 | 1014888 |
| 8 | 8241792 |
| 9 | 66724398 |
| 10 | 538990800 |
| 11 | 4346692680 |
| 12 | 35009591040 |
| 13 | 281699380560 |
| 14 | 2264868936960 |
| 15 | 18198009147600 |
| 16 | 146142982814208 |
| 17 | 1173123636533454 |
| 18 | 9413509300965936 |
| 19 | 75513633110271264 |
| 20 | 605598295606296000 |
| 21 | 4855626127979443908 |
| 22 | 38924245740546950784 |
[3,24,216,1824,15150,124416,1014888,8241792, 66724398,538990800,4346692680,35009591040, 281699380560,2264868936960,18198009147600, 146142982814208,1173123636533454,9413509300965936, 75513633110271264,605598295606296000, 4855626127979443908,38924245740546950784] |