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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 8 |
| 4 | 28 |
| 5 | 91 |
| 6 | 325 |
| 7 | 1148 |
| 8 | 4210 |
| 9 | 15417 |
| 10 | 57694 |
| 11 | 215581 |
| 12 | 817502 |
| 13 | 3096572 |
| 14 | 11845074 |
| 15 | 45302298 |
| 16 | 174388276 |
| 17 | 671564376 |
| 18 | 2597822666 |
| 19 | 10054975765 |
| 20 | 39046176946 |
| 21 | 151720773774 |
| 22 | 590988865435 |
| 23 | 2303515089701 |
| 24 | 8995278200261 |
| 25 | 35149053029039 |
| 26 | 137544582434822 |
| 27 | 538562601081153 |
| 28 | 2111208646798646 |
[1,1,3,8,28,91,325,1148,4210,15417,57694,215581, 817502,3096572,11845074,45302298,174388276, 671564376,2597822666,10054975765,39046176946, 151720773774,590988865435,2303515089701, 8995278200261,35149053029039,137544582434822, 538562601081153,2111208646798646] |