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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 31 |
| 5 | 293 |
| 6 | 3326 |
| 7 | 44189 |
| 8 | 673471 |
| 9 | 11588884 |
| 10 | 222304897 |
| 11 | 4704612119 |
[0,1,4,31,293,3326,44189,673471,11588884, 222304897,4704612119] |