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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 10 |
| 2 | 80 |
| 3 | 560 |
| 4 | 3640 |
| 5 | 22512 |
| 6 | 134400 |
| 7 | 781440 |
| 8 | 4451040 |
| 9 | 24939200 |
| 10 | 137865728 |
| 11 | 753625600 |
| 12 | 4080643840 |
| 13 | 21916106240 |
| 14 | 116877312000 |
| 15 | 619457482752 |
| 16 | 3265293719040 |
| 17 | 17128725519360 |
| 18 | 89462514606080 |
| 19 | 465434423336960 |
| 20 | 2412895587536896 |
| 21 | 12468681310412800 |
| 22 | 64242981906022400 |
[1,10,80,560,3640,22512,134400,781440,4451040, 24939200,137865728,753625600,4080643840, 21916106240,116877312000,619457482752, 3265293719040,17128725519360,89462514606080, 465434423336960,2412895587536896, 12468681310412800,64242981906022400] |