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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 54 |
| 4 | 259 |
| 5 | 1292 |
| 6 | 6616 |
| 7 | 34507 |
| 8 | 182395 |
| 9 | 973691 |
| 10 | 5236794 |
| 11 | 28323936 |
| 12 | 153842660 |
| 13 | 838210232 |
| 14 | 4577088300 |
| 15 | 25029752243 |
| 16 | 136984351418 |
| 17 | 749861003157 |
| 18 | 4103514165744 |
| 19 | 22437771907824 |
| 20 | 122529735856669 |
| 21 | 667928556599614 |
| 22 | 3632677249330084 |
| 23 | 19701490439727844 |
[1,3,12,54,259,1292,6616,34507,182395,973691, 5236794,28323936,153842660,838210232,4577088300, 25029752243,136984351418,749861003157, 4103514165744,22437771907824,122529735856669, 667928556599614,3632677249330084, 19701490439727844] |