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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 8 |
| 4 | 61 |
| 5 | 472 |
| 6 | 4050 |
| 7 | 36454 |
| 8 | 341988 |
| 9 | 3306612 |
| 10 | 32757830 |
| 11 | 330964946 |
| 12 | 3398830478 |
| 13 | 35386215292 |
| 14 | 372754193214 |
| 15 | 3966423984516 |
| 16 | 42579631811396 |
| 17 | 460648926971334 |
| 18 | 5017891492413126 |
| 19 | 54996459314116816 |
| 20 | 606092251444553993 |
[0,2,8,61,472,4050,36454,341988,3306612,32757830, 330964946,3398830478,35386215292,372754193214, 3966423984516,42579631811396,460648926971334, 5017891492413126,54996459314116816, 606092251444553993] |