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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 16 |
| 3 | 214 |
| 4 | 4030 |
| 5 | 98020 |
| 6 | 2923580 |
| 7 | 103306320 |
| 8 | 4219788720 |
| 9 | 195631761360 |
| 10 | 10148327972160 |
| 11 | 582405469831920 |
| 12 | 36635844203963760 |
| 13 | 2506613821744700640 |
| 14 | 185327181909308762400 |
| 15 | 14724431257109269113600 |
| 16 | 1251088847268683450630400 |
| 17 | 113202071235423519573369600 |
[1,2,16,214,4030,98020,2923580,103306320, 4219788720,195631761360,10148327972160, 582405469831920,36635844203963760, 2506613821744700640,185327181909308762400, 14724431257109269113600,1251088847268683450630400, 113202071235423519573369600] |