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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 19 |
| 6 | 40 |
| 7 | 85 |
| 8 | 180 |
| 9 | 381 |
| 10 | 807 |
| 11 | 1709 |
| 12 | 3619 |
| 13 | 7664 |
| 14 | 16230 |
| 15 | 34370 |
| 16 | 72785 |
| 17 | 154136 |
| 18 | 326412 |
| 19 | 691239 |
| 20 | 1463829 |
| 21 | 3099934 |
| 22 | 6564695 |
| 23 | 13901980 |
| 24 | 29440065 |
| 25 | 62344891 |
| 26 | 132027067 |
| 27 | 279592219 |
| 28 | 592089264 |
| 29 | 1253860704 |
| 30 | 2655286560 |
[1,1,2,4,9,19,40,85,180,381,807,1709,3619,7664, 16230,34370,72785,154136,326412,691239,1463829, 3099934,6564695,13901980,29440065,62344891, 132027067,279592219,592089264,1253860704, 2655286560] |