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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 8 |
| 3 | 28 |
| 4 | 84 |
| 5 | 242 |
| 6 | 744 |
| 7 | 2284 |
| 8 | 7096 |
| 9 | 22179 |
| 10 | 69561 |
| 11 | 218759 |
| 12 | 689206 |
| 13 | 2173942 |
| 14 | 6862783 |
| 15 | 21676671 |
| 16 | 68493153 |
| 17 | 216477260 |
| 18 | 684309327 |
| 19 | 2163434093 |
| 20 | 6840212693 |
| 21 | 21628140126 |
| 22 | 68388775913 |
| 23 | 216252650605 |
| 24 | 683825838922 |
| 25 | 2162393136881 |
| 26 | 6837971108286 |
| 27 | 21623312527390 |
| 28 | 68378377967873 |
[4,8,28,84,242,744,2284,7096,22179,69561,218759, 689206,2173942,6862783,21676671,68493153, 216477260,684309327,2163434093,6840212693, 21628140126,68388775913,216252650605,683825838922, 2162393136881,6837971108286,21623312527390, 68378377967873] |