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| n | a(n) |
|---|---|
| 1 | 9 |
| 2 | 21 |
| 3 | 49 |
| 4 | 115 |
| 5 | 269 |
| 6 | 631 |
| 7 | 1477 |
| 8 | 3463 |
| 9 | 8109 |
| 10 | 19007 |
| 11 | 44517 |
| 12 | 104327 |
| 13 | 244381 |
| 14 | 572655 |
| 15 | 1341525 |
| 16 | 3143383 |
| 17 | 7364173 |
| 18 | 17254655 |
| 19 | 40424581 |
| 20 | 94714855 |
| 21 | 221903869 |
| 22 | 519914127 |
| 23 | 1218099893 |
| 24 | 2853948663 |
| 25 | 6686519981 |
| 26 | 15666114847 |
| 27 | 36704297445 |
| 28 | 85995716871 |
[9,21,49,115,269,631,1477,3463,8109,19007,44517, 104327,244381,572655,1341525,3143383,7364173, 17254655,40424581,94714855,221903869,519914127, 1218099893,2853948663,6686519981,15666114847, 36704297445,85995716871] |