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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 11 |
| 5 | 57 |
| 6 | 126 |
| 7 | 17609 |
| 8 | 127439468 |
| 9 | 344473534513077 |
| 10 | 891027683693605833852 |
| 11 | 156052046552117500148945259643265853536683707838813 |
[1,1,2,5,11,57,126,17609,127439468, 344473534513077,891027683693605833852, 15605204655211750014894525964326585353668370783881\ 3] |