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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 23 |
| 6 | 59 |
| 7 | 155 |
| 8 | 418 |
| 9 | 1136 |
| 10 | 3122 |
| 11 | 8663 |
| 12 | 24201 |
| 13 | 68059 |
| 14 | 192471 |
| 15 | 546899 |
| 16 | 1560511 |
| 17 | 4469000 |
| 18 | 12839642 |
| 19 | 36995629 |
| 20 | 106875531 |
| 21 | 309477998 |
| 22 | 898075778 |
| 23 | 2611239508 |
| 24 | 7606064348 |
| 25 | 22191694916 |
| 26 | 64845964156 |
| 27 | 189752911736 |
| 28 | 555985221037 |
| 29 | 1631053277370 |
| 30 | 4790356866561 |
[1,2,4,9,23,59,155,418,1136,3122,8663,24201,68059, 192471,546899,1560511,4469000,12839642,36995629, 106875531,309477998,898075778,2611239508, 7606064348,22191694916,64845964156,189752911736, 555985221037,1631053277370,4790356866561] |