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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 8 |
| 3 | 18 |
| 4 | 36 |
| 5 | 66 |
| 6 | 120 |
| 7 | 210 |
| 8 | 360 |
| 9 | 618 |
| 10 | 1052 |
| 11 | 1790 |
| 12 | 3040 |
| 13 | 5162 |
| 14 | 8756 |
| 15 | 14854 |
| 16 | 25192 |
| 17 | 42722 |
| 18 | 72444 |
| 19 | 122846 |
| 20 | 208304 |
| 21 | 353210 |
[2,8,18,36,66,120,210,360,618,1052,1790,3040,5162, 8756,14854,25192,42722,72444,122846,208304,353210] |