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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 12 |
| 3 | 25 |
| 4 | 51 |
| 5 | 165 |
| 6 | 419 |
| 7 | 1009 |
| 8 | 2697 |
| 9 | 7091 |
| 10 | 18147 |
| 11 | 46901 |
| 12 | 122403 |
| 13 | 317379 |
| 14 | 820951 |
| 15 | 2131357 |
| 16 | 5532371 |
| 17 | 14340367 |
| 18 | 37190407 |
| 19 | 96488757 |
| 20 | 250257339 |
| 21 | 649031555 |
| 22 | 1683483587 |
| 23 | 4366629269 |
| 24 | 11325556739 |
| 25 | 29375297911 |
| 26 | 76192462975 |
| 27 | 197622279245 |
[4,12,25,51,165,419,1009,2697,7091,18147,46901, 122403,317379,820951,2131357,5532371,14340367, 37190407,96488757,250257339,649031555,1683483587, 4366629269,11325556739,29375297911,76192462975, 197622279245] |