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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 6 |
| 5 | 32 |
| 6 | 195 |
| 7 | 1398 |
| 8 | 11375 |
| 9 | 103744 |
| 10 | 1048653 |
| 11 | 11637720 |
| 12 | 140691287 |
| 13 | 1840531920 |
| 14 | 25907192051 |
| 15 | 390437813612 |
| 16 | 6272783063745 |
| 17 | 107026049110528 |
| 18 | 1932717589794045 |
| 19 | 36828295595429724 |
| 20 | 738492745452351643 |
[0,1,1,6,32,195,1398,11375,103744,1048653, 11637720,140691287,1840531920,25907192051, 390437813612,6272783063745,107026049110528, 1932717589794045,36828295595429724, 738492745452351643] |