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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 3 |
| 4 | 5 |
| 5 | 13 |
| 6 | 33 |
| 7 | 153 |
| 8 | 285 |
| 9 | 713 |
| 10 | 5795 |
| 11 | 18445 |
| 12 | 90363 |
| 13 | 304589 |
| 14 | 1013725 |
| 15 | 5617820 |
| 16 | 23738713 |
| 17 | 123702369 |
| 18 | 556876529 |
| 19 | 3760113565 |
| 20 | 18723991845 |
| 21 | 41704979953 |
[1,3,5,13,33,153,285,713,5795,18445,90363,304589, 1013725,5617820,23738713,123702369,556876529, 3760113565,18723991845,41704979953] |