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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 23 |
| 7 | 65 |
| 8 | 199 |
| 9 | 653 |
| 10 | 2275 |
| 11 | 8313 |
| 12 | 31439 |
| 13 | 121637 |
| 14 | 477307 |
| 15 | 1888721 |
| 16 | 7509799 |
| 17 | 29940861 |
| 18 | 119550419 |
| 19 | 477742889 |
| 20 | 1909988479 |
| 21 | 7637856725 |
| 22 | 30546970411 |
| 23 | 122178444417 |
| 24 | 488693854679 |
| 25 | 1954733475629 |
| 26 | 7818845822083 |
| 27 | 31275198738905 |
[1,1,2,4,9,23,65,199,653,2275,8313,31439,121637, 477307,1888721,7509799,29940861,119550419, 477742889,1909988479,7637856725,30546970411, 122178444417,488693854679,1954733475629, 7818845822083,31275198738905] |