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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 16 |
| 3 | 222 |
| 4 | 4416 |
| 5 | 114660 |
| 6 | 3676814 |
| 7 | 140408338 |
| 8 | 6222858240 |
| 9 | 314006546124 |
| 10 | 17774855765140 |
| 11 | 1115507717954432 |
| 12 | 76871991664546170 |
| 13 | 5770732305836768712 |
| 14 | 468750121409142448386 |
| 15 | 40964179307489016777630 |
| 16 | 3832326196169482368117760 |
[1,2,16,222,4416,114660,3676814,140408338, 6222858240,314006546124,17774855765140, 1115507717954432,76871991664546170, 5770732305836768712,468750121409142448386, 40964179307489016777630,3832326196169482368117760] |