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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 16 |
| 4 | 152 |
| 5 | 1721 |
| 6 | 21083 |
| 7 | 217825 |
| 8 | 2135214 |
| 9 | 20752645 |
| 10 | 208916566 |
| 11 | 2138876698 |
[1,2,16,152,1721,21083,217825,2135214,20752645, 208916566,2138876698] |