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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 48 |
| 5 | 368 |
| 6 | 3376 |
| 7 | 35824 |
| 8 | 430512 |
| 9 | 5773936 |
| 10 | 85482032 |
| 11 | 1384936688 |
| 12 | 24380214960 |
| 13 | 463522810736 |
| 14 | 9468048895792 |
| 15 | 206831329017328 |
| 16 | 4812581925690288 |
| 17 | 118843801816575088 |
| 18 | 3104590192664327216 |
| 19 | 85544737118902122224 |
| 20 | 2479681575659312797872 |
| 21 | 75434373300016828382576 |
[1,2,8,48,368,3376,35824,430512,5773936,85482032, 1384936688,24380214960,463522810736,9468048895792, 206831329017328,4812581925690288, 118843801816575088,3104590192664327216, 85544737118902122224,2479681575659312797872, 75434373300016828382576] |