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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 120 |
| 2 | 3920 |
| 3 | 115500 |
| 4 | 3279276 |
| 5 | 91483392 |
| 6 | 2527462080 |
| 7 | 69413752980 |
| 8 | 1898945262500 |
| 9 | 51809303385840 |
| 10 | 1410778953118080 |
| 11 | 38360293308573600 |
| 12 | 1041896542898685600 |
| 13 | 28274302212143040000 |
| 14 | 766761376923703054080 |
| 15 | 20781963787558897929060 |
| 16 | 563007692048242597348500 |
| 17 | 15246741943087253044446000 |
[2,120,3920,115500,3279276,91483392,2527462080, 69413752980,1898945262500,51809303385840, 1410778953118080,38360293308573600, 1041896542898685600,28274302212143040000, 766761376923703054080,20781963787558897929060, 563007692048242597348500, 15246741943087253044446000] |