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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 23 |
| 4 | 84 |
| 5 | 283 |
| 6 | 930 |
| 7 | 2921 |
| 8 | 9096 |
| 9 | 27507 |
| 10 | 82930 |
| 11 | 244819 |
| 12 | 722116 |
| 13 | 2096603 |
| 14 | 6087290 |
| 15 | 17458887 |
| 16 | 50090544 |
| 17 | 142317089 |
| 18 | 404543142 |
[1,6,23,84,283,930,2921,9096,27507,82930,244819, 722116,2096603,6087290,17458887,50090544, 142317089,404543142] |