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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 45 |
| 4 | 1436 |
| 5 | 171836 |
| 6 | 68149425 |
| 7 | 89431630740 |
| 8 | 396956313475102 |
| 9 | 6099399658235428041 |
| 10 | 331007760926212498510464 |
| 11 | 64484289650612910347505873728 |
| 12 | 45677712418497545460138258802186905 |
[1,2,6,45,1436,171836,68149425,89431630740, 396956313475102,6099399658235428041, 331007760926212498510464, 64484289650612910347505873728, 45677712418497545460138258802186905] |