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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 3 |
| 3 | 10 |
| 4 | 119 |
| 5 | 791 |
| 6 | 8823 |
| 7 | 87515 |
| 8 | 1042823 |
| 9 | 12448912 |
| 10 | 166443706 |
| 11 | 2246438833 |
| 12 | 32782857721 |
| 13 | 488717384754 |
| 14 | 7695520330054 |
| 15 | 124248088106249 |
| 16 | 2091672883631855 |
| 17 | 36107381616662300 |
| 18 | 644987804706582806 |
| 19 | 11799406380611542654 |
| 20 | 222235188242044718908 |
| 21 | 4280160250751484220674 |
[1,0,3,10,119,791,8823,87515,1042823,12448912, 166443706,2246438833,32782857721,488717384754, 7695520330054,124248088106249,2091672883631855, 36107381616662300,644987804706582806, 11799406380611542654,222235188242044718908, 4280160250751484220674] |