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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 3 |
| 2 | 7 |
| 3 | 19 |
| 4 | 56 |
| 5 | 174 |
| 6 | 561 |
| 7 | 1859 |
| 8 | 6292 |
| 9 | 21658 |
| 10 | 75582 |
| 11 | 266798 |
| 12 | 950912 |
| 13 | 3417340 |
| 14 | 12369285 |
| 15 | 45052515 |
| 16 | 165002460 |
| 17 | 607283490 |
| 18 | 2244901890 |
| 19 | 8331383610 |
| 20 | 31030387440 |
| 21 | 115948830660 |
| 22 | 434542177290 |
| 23 | 1632963760974 |
| 24 | 6151850548776 |
[2,3,7,19,56,174,561,1859,6292,21658,75582,266798, 950912,3417340,12369285,45052515,165002460, 607283490,2244901890,8331383610,31030387440, 115948830660,434542177290,1632963760974, 6151850548776] |