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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 9 |
| 4 | 23 |
| 5 | 65 |
| 6 | 197 |
| 7 | 626 |
| 8 | 2056 |
| 9 | 6918 |
| 10 | 23714 |
| 11 | 82500 |
| 12 | 290512 |
| 13 | 1033412 |
| 14 | 3707852 |
| 15 | 13402697 |
| 16 | 48760367 |
| 17 | 178405157 |
| 18 | 656043857 |
| 19 | 2423307047 |
| 20 | 8987427467 |
| 21 | 33453694487 |
| 22 | 124936258127 |
| 23 | 467995871777 |
| 24 | 1757900019101 |
| 25 | 6619846420553 |
| 26 | 24987199492705 |
| 27 | 94520750408709 |
| 28 | 358268702159069 |
[1,2,4,9,23,65,197,626,2056,6918,23714,82500, 290512,1033412,3707852,13402697,48760367, 178405157,656043857,2423307047,8987427467, 33453694487,124936258127,467995871777, 1757900019101,6619846420553,24987199492705, 94520750408709,358268702159069] |