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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 7 |
| 3 | 24 |
| 4 | 80 |
| 5 | 238 |
| 6 | 723 |
| 7 | 2183 |
| 8 | 5653 |
| 9 | 19674 |
| 10 | 59042 |
| 11 | 177145 |
| 12 | 531429 |
| 13 | 1594313 |
| 14 | 4782955 |
| 15 | 14348892 |
| 16 | 43046708 |
| 17 | 129140146 |
| 18 | 387420471 |
| 19 | 1162261451 |
| 20 | 3486784397 |
| 21 | 10460353182 |
| 22 | 31381059590 |
| 23 | 94143178804 |
| 24 | 282429536457 |
| 25 | 847288609421 |
[2,7,24,80,238,723,2183,5653,19674,59042,177145, 531429,1594313,4782955,14348892,43046708, 129140146,387420471,1162261451,3486784397, 10460353182,31381059590,94143178804,282429536457, 847288609421] |