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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 3 |
| 3 | 10 |
| 4 | 65 |
| 5 | 476 |
| 6 | 4207 |
| 7 | 43086 |
| 8 | 502749 |
| 9 | 6584512 |
| 10 | 95663051 |
| 11 | 1526969522 |
| 12 | 26564598073 |
| 13 | 500293750308 |
| 14 | 10141049220135 |
| 15 | 220142141757718 |
| 16 | 5095512540223637 |
| 17 | 125275254488912264 |
| 18 | 3260259408767933059 |
| 19 | 89541327910560478074 |
| 20 | 2588146468333823725041 |
[1,0,3,10,65,476,4207,43086,502749,6584512, 95663051,1526969522,26564598073,500293750308, 10141049220135,220142141757718,5095512540223637, 125275254488912264,3260259408767933059, 89541327910560478074,2588146468333823725041] |