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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 6 |
| 3 | 13 |
| 4 | 26 |
| 5 | 48 |
| 6 | 121 |
| 7 | 275 |
| 8 | 600 |
| 9 | 1296 |
| 10 | 2998 |
| 11 | 6731 |
| 12 | 15022 |
| 13 | 33412 |
| 14 | 75480 |
| 15 | 169232 |
| 16 | 379265 |
| 17 | 848913 |
| 18 | 1907065 |
| 19 | 4276079 |
| 20 | 9589159 |
| 21 | 21494910 |
| 22 | 48224727 |
| 23 | 108142434 |
| 24 | 242526545 |
| 25 | 543834226 |
| 26 | 1219737296 |
| 27 | 2735350513 |
| 28 | 6134430103 |
| 29 | 13756843652 |
| 30 | 30852213480 |
[4,6,13,26,48,121,275,600,1296,2998,6731,15022, 33412,75480,169232,379265,848913,1907065,4276079, 9589159,21494910,48224727,108142434,242526545, 543834226,1219737296,2735350513,6134430103, 13756843652,30852213480] |