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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 10 |
| 3 | 180 |
| 4 | 4440 |
| 5 | 135525 |
| 6 | 4866156 |
| 7 | 199577910 |
| 8 | 9174096960 |
| 9 | 466435229220 |
| 10 | 25973117225450 |
| 11 | 1571873641094680 |
| 12 | 102741164109622800 |
| 13 | 7214517196021315830 |
| 14 | 541781124945022815720 |
| 15 | 43336510897320779553450 |
[1,1,10,180,4440,135525,4866156,199577910, 9174096960,466435229220,25973117225450, 1571873641094680,102741164109622800, 7214517196021315830,541781124945022815720, 43336510897320779553450] |