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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 12 |
| 3 | 96 |
| 4 | 879 |
| 5 | 8712 |
| 6 | 90972 |
| 7 | 985728 |
| 8 | 10979577 |
| 9 | 124937892 |
| 10 | 1446119664 |
| 11 | 16972881120 |
| 12 | 201526230555 |
| 13 | 2416309004872 |
| 14 | 29215072931136 |
| 15 | 355800894005760 |
| 16 | 4360705642282569 |
| 17 | 53744080256387478 |
| 18 | 665667989498682936 |
| 19 | 8281518339078928800 |
| 20 | 103441301833577854041 |
| 21 | 1296713265300164761632 |
[1,2,12,96,879,8712,90972,985728,10979577, 124937892,1446119664,16972881120,201526230555, 2416309004872,29215072931136,355800894005760, 4360705642282569,53744080256387478, 665667989498682936,8281518339078928800, 103441301833577854041,1296713265300164761632] |