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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 10 |
| 4 | 60 |
| 5 | 468 |
| 6 | 4263 |
| 7 | 44727 |
| 8 | 525780 |
| 9 | 6830481 |
| 10 | 96839125 |
| 11 | 1484711160 |
| 12 | 24430435406 |
| 13 | 428792862307 |
| 14 | 7986273135870 |
| 15 | 157151111302530 |
| 16 | 3254838706878084 |
| 17 | 70722431837010468 |
| 18 | 1607504293142601861 |
| 19 | 38125031159774883774 |
| 20 | 941342645386473873648 |
| 21 | 24148088913729608830269 |
[1,2,10,60,468,4263,44727,525780,6830481,96839125, 1484711160,24430435406,428792862307,7986273135870, 157151111302530,3254838706878084, 70722431837010468,1607504293142601861, 38125031159774883774,941342645386473873648, 24148088913729608830269] |