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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 14 |
| 3 | 150 |
| 4 | 1456 |
| 5 | 13484 |
| 6 | 121800 |
| 7 | 1084936 |
| 8 | 9586304 |
| 9 | 84301200 |
| 10 | 739246816 |
| 11 | 6471600224 |
| 12 | 56597049600 |
| 13 | 494665084096 |
| 14 | 4321846895744 |
| 15 | 37751262672000 |
| 16 | 329712720203776 |
| 17 | 2879419999940864 |
| 18 | 25145094869798400 |
| 19 | 219578008179897856 |
| 20 | 1917417750507843584 |
[1,14,150,1456,13484,121800,1084936,9586304, 84301200,739246816,6471600224,56597049600, 494665084096,4321846895744,37751262672000, 329712720203776,2879419999940864, 25145094869798400,219578008179897856, 1917417750507843584] |