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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 63 |
| 4 | 790 |
| 5 | 10896 |
| 6 | 159783 |
| 7 | 2445499 |
| 8 | 38627339 |
| 9 | 625074945 |
| 10 | 10310825610 |
| 11 | 172747624244 |
| 12 | 2931749347058 |
| 13 | 50298296409267 |
| 14 | 870968173547912 |
| 15 | 15202903269996956 |
| 16 | 267229314929729201 |
| 17 | 4726210689606805342 |
| 18 | 84045293131256519705 |
| 19 | 1501874060469604610959 |
[1,1,6,63,790,10896,159783,2445499,38627339, 625074945,10310825610,172747624244,2931749347058, 50298296409267,870968173547912,15202903269996956, 267229314929729201,4726210689606805342, 84045293131256519705,1501874060469604610959] |