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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 3 |
| 3 | 74 |
| 4 | 1220 |
| 5 | 12910 |
| 6 | 100807 |
| 7 | 652343 |
| 8 | 3750182 |
| 9 | 19784428 |
| 10 | 96786947 |
| 11 | 439906101 |
| 12 | 1859501560 |
| 13 | 7328752206 |
| 14 | 27039030100 |
| 15 | 93829708460 |
| 16 | 307762056698 |
| 17 | 958683800155 |
| 18 | 2848583303210 |
| 19 | 8105942966932 |
| 20 | 22169003715353 |
| 21 | 58456685214757 |
[0,3,74,1220,12910,100807,652343,3750182,19784428, 96786947,439906101,1859501560,7328752206, 27039030100,93829708460,307762056698,958683800155, 2848583303210,8105942966932,22169003715353, 58456685214757] |