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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 3 |
| 8 | 13 |
| 9 | 33 |
| 10 | 61 |
| 11 | 123 |
| 12 | 351 |
| 13 | 1083 |
| 14 | 3363 |
| 15 | 12745 |
| 16 | 54981 |
| 17 | 257267 |
| 18 | 1349181 |
| 19 | 7264663 |
| 20 | 42437683 |
| 21 | 269731743 |
[1,1,1,1,1,1,3,13,33,61,123,351,1083,3363,12745, 54981,257267,1349181,7264663,42437683,269731743] |