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| n | a(n) |
|---|---|
| 0 | 3 |
| 1 | 15 |
| 2 | 57 |
| 3 | 192 |
| 4 | 567 |
| 5 | 1683 |
| 6 | 4392 |
| 7 | 12084 |
| 8 | 29073 |
| 9 | 75753 |
| 10 | 172269 |
| 11 | 430248 |
| 12 | 938784 |
| 13 | 2272308 |
| 14 | 4793652 |
| 15 | 11202642 |
| 16 | 22952439 |
| 17 | 52535655 |
| 18 | 105206253 |
| 19 | 233047158 |
| 20 | 455660913 |
| 21 | 996014343 |
| 22 | 1917372474 |
| 23 | 4062940566 |
| 24 | 7660442568 |
| 25 | 16114463106 |
[3,15,57,192,567,1683,4392,12084,29073,75753, 172269,430248,938784,2272308,4793652,11202642, 22952439,52535655,105206253,233047158,455660913, 996014343,1917372474,4062940566,7660442568, 16114463106] |