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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 32 |
| 5 | 160 |
| 6 | 1000 |
| 7 | 7000 |
| 8 | 56000 |
| 9 | 506240 |
| 10 | 5062400 |
| 11 | 55686400 |
| 12 | 668483200 |
| 13 | 8690281600 |
| 14 | 121663942400 |
| 15 | 1825003980800 |
| 16 | 29200063692800 |
| 17 | 496401082777600 |
| 18 | 8935231687782400 |
| 19 | 169769402067865600 |
| 20 | 3395388041357312000 |
| 21 | 71303153503662080000 |
| 22 | 1568669377080565760000 |
| 23 | 36079395672853012480000 |
[1,1,2,8,32,160,1000,7000,56000,506240,5062400, 55686400,668483200,8690281600,121663942400, 1825003980800,29200063692800,496401082777600, 8935231687782400,169769402067865600, 3395388041357312000,71303153503662080000, 1568669377080565760000,36079395672853012480000] |