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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 23 |
| 5 | 69 |
| 6 | 206 |
| 7 | 616 |
| 8 | 1846 |
| 9 | 5537 |
| 10 | 16609 |
| 11 | 49824 |
| 12 | 149469 |
| 13 | 448405 |
| 14 | 1345212 |
| 15 | 4035632 |
| 16 | 12106892 |
| 17 | 36320673 |
| 18 | 108962015 |
| 19 | 326886040 |
| 20 | 980658115 |
| 21 | 2941974341 |
| 22 | 8825923018 |
| 23 | 26477769048 |
| 24 | 79433307138 |
| 25 | 238299921409 |
| 26 | 714899764221 |
| 27 | 2144699292656 |
[1,3,8,23,69,206,616,1846,5537,16609,49824,149469, 448405,1345212,4035632,12106892,36320673, 108962015,326886040,980658115,2941974341, 8825923018,26477769048,79433307138,238299921409, 714899764221,2144699292656] |