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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 70 |
| 3 | 910 |
| 4 | 14560 |
| 5 | 276640 |
| 6 | 6086080 |
| 7 | 152152000 |
| 8 | 4260256000 |
| 9 | 132067936000 |
| 10 | 4490309824000 |
| 11 | 166141463488000 |
| 12 | 6645658539520000 |
| 13 | 285763317199360000 |
| 14 | 13145112591170560000 |
| 15 | 644110516967357440000 |
| 16 | 33493746882302586880000 |
| 17 | 1842156078526642278400000 |
[1,7,70,910,14560,276640,6086080,152152000, 4260256000,132067936000,4490309824000, 166141463488000,6645658539520000, 285763317199360000,13145112591170560000, 644110516967357440000,33493746882302586880000, 1842156078526642278400000] |