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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 13 |
| 3 | 35 |
| 4 | 103 |
| 5 | 278 |
| 6 | 763 |
| 7 | 2037 |
| 8 | 5421 |
| 9 | 14264 |
| 10 | 37321 |
| 11 | 97015 |
| 12 | 250963 |
| 13 | 646250 |
| 14 | 1657719 |
| 15 | 4237481 |
| 16 | 10798553 |
| 17 | 27442092 |
| 18 | 69563653 |
| 19 | 175938699 |
| 20 | 444060607 |
| 21 | 1118668286 |
| 22 | 2813233523 |
| 23 | 7063416349 |
| 24 | 17708464645 |
| 25 | 44335423456 |
| 26 | 110857865665 |
| 27 | 276863340767 |
[4,13,35,103,278,763,2037,5421,14264,37321,97015, 250963,646250,1657719,4237481,10798553,27442092, 69563653,175938699,444060607,1118668286, 2813233523,7063416349,17708464645,44335423456, 110857865665,276863340767] |