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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 56 |
| 5 | 288 |
| 6 | 1584 |
| 7 | 9152 |
| 8 | 54912 |
| 9 | 339456 |
| 10 | 2149888 |
| 11 | 13891584 |
| 12 | 91287552 |
| 13 | 608583680 |
| 14 | 4107939840 |
| 15 | 28030648320 |
| 16 | 193100021760 |
| 17 | 1341536993280 |
| 18 | 9390758952960 |
| 19 | 66182491668480 |
| 20 | 469294031831040 |
| 21 | 3346270487838720 |
| 22 | 23981605162844160 |
| 23 | 172667557172477952 |
[1,1,3,12,56,288,1584,9152,54912,339456,2149888, 13891584,91287552,608583680,4107939840, 28030648320,193100021760,1341536993280, 9390758952960,66182491668480,469294031831040, 3346270487838720,23981605162844160, 172667557172477952] |