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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 60 |
| 4 | 1320 |
| 5 | 46200 |
| 6 | 2356200 |
| 7 | 164934000 |
| 8 | 15173928000 |
| 9 | 1775349576000 |
| 10 | 257425688520000 |
| 11 | 45306921179520000 |
| 12 | 9514453447699200000 |
| 13 | 2350070001581702400000 |
| 14 | 674470090453948588800000 |
| 15 | 222575129849803034304000000 |
[1,1,5,60,1320,46200,2356200,164934000, 15173928000,1775349576000,257425688520000, 45306921179520000,9514453447699200000, 2350070001581702400000,674470090453948588800000, 222575129849803034304000000] |