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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 18 |
| 4 | 27 |
| 5 | 648 |
| 6 | 68040 |
| 7 | 136080 |
| 8 | 51030 |
| 9 | 653184 |
| 10 | 4849891200 |
| 11 | 203695430400 |
| 12 | 43649020800 |
| 13 | 1466607098880 |
| 14 | 285988384281600 |
| 15 | 8579651528448000 |
| 16 | 15014390174784000 |
| 17 | 64061398079078400 |
| 18 | 2793397263238213632000 |
| 19 | 184364219373722099712000 |
| 20 | 9669452065055354880000 |
| 21 | 46459783282177969127424000 |
| 22 | 16028625232351399348961280000 |
[1,1,3,18,27,648,68040,136080,51030,653184, 4849891200,203695430400,43649020800,1466607098880, 285988384281600,8579651528448000, 15014390174784000,64061398079078400, 2793397263238213632000,184364219373722099712000, 9669452065055354880000,46459783282177969127424000, 16028625232351399348961280000] |