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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 13 |
| 5 | 20 |
| 6 | 62 |
| 7 | 113 |
| 8 | 224 |
| 9 | 367 |
| 10 | 494 |
| 11 | 833 |
| 12 | 9169 |
| 13 | 131313 |
| 14 | 155719 |
| 15 | 180118 |
| 16 | 280766754 |
| 17 | 3454917187 |
| 18 | 31685027464 |
| 19 | 152431947617 |
| 20 | 629621648241 |
[1,3,6,13,20,62,113,224,367,494,833,9169,131313, 155719,180118,280766754,3454917187,31685027464, 152431947617,629621648241] |