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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 2 |
| 2 | 5 |
| 3 | 9 |
| 4 | 19 |
| 5 | 40 |
| 6 | 88 |
| 7 | 198 |
| 8 | 455 |
| 9 | 1061 |
| 10 | 2501 |
| 11 | 5940 |
| 12 | 14182 |
| 13 | 33982 |
| 14 | 81625 |
| 15 | 196389 |
| 16 | 473039 |
| 17 | 1140260 |
| 18 | 2749988 |
| 19 | 6634458 |
| 20 | 16009555 |
| 21 | 38638441 |
| 22 | 93261961 |
| 23 | 225122760 |
| 24 | 543443402 |
| 25 | 1311905882 |
| 26 | 3167087405 |
| 27 | 7645809249 |
| 28 | 18458266699 |
| 29 | 44561632000 |
[2,2,5,9,19,40,88,198,455,1061,2501,5940,14182, 33982,81625,196389,473039,1140260,2749988,6634458, 16009555,38638441,93261961,225122760,543443402, 1311905882,3167087405,7645809249,18458266699, 44561632000] |