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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 3 |
| 2 | 18 |
| 3 | 128 |
| 4 | 2100 |
| 5 | 61600 |
| 6 | 3732480 |
| 7 | 449880480 |
| 8 | 111021510600 |
| 9 | 55916730777600 |
| 10 | 57813913372723200 |
| 11 | 122742264040428032000 |
| 12 | 535797463154791219200000 |
| 13 | 4810427190599491339840000000 |
| 14 | 88856328051357049141036014736800 |
| 15 | 3377300175611111321142254817509376000 |
[2,3,18,128,2100,61600,3732480,449880480, 111021510600,55916730777600,57813913372723200, 122742264040428032000,535797463154791219200000, 4810427190599491339840000000, 88856328051357049141036014736800, 3377300175611111321142254817509376000] |