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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 6 |
| 3 | 19 |
| 4 | 59 |
| 5 | 177 |
| 6 | 532 |
| 7 | 1598 |
| 8 | 4794 |
| 9 | 14383 |
| 10 | 43151 |
| 11 | 129453 |
| 12 | 388360 |
| 13 | 1165082 |
| 14 | 3495246 |
| 15 | 10485739 |
| 16 | 31457219 |
| 17 | 94371657 |
| 18 | 283114972 |
| 19 | 849344918 |
| 20 | 2548034754 |
| 21 | 7644104263 |
| 22 | 22932312791 |
| 23 | 68796938373 |
| 24 | 206390815120 |
| 25 | 619172445362 |
[2,6,19,59,177,532,1598,4794,14383,43151,129453, 388360,1165082,3495246,10485739,31457219,94371657, 283114972,849344918,2548034754,7644104263, 22932312791,68796938373,206390815120,619172445362] |