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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 12 |
| 4 | 144 |
| 5 | 2400 |
| 6 | 50400 |
| 7 | 1290240 |
| 8 | 39070080 |
| 9 | 1365154560 |
| 10 | 54047347200 |
| 11 | 2391175987200 |
| 12 | 116918542540800 |
| 13 | 6260970517401600 |
| 14 | 364413626331955200 |
| 15 | 22906448213096448000 |
| 16 | 1546480919558615040000 |
| 17 | 111605770820457897984000 |
[0,1,2,12,144,2400,50400,1290240,39070080, 1365154560,54047347200,2391175987200, 116918542540800,6260970517401600, 364413626331955200,22906448213096448000, 1546480919558615040000,111605770820457897984000] |