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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 9 |
| 4 | 18 |
| 5 | 37 |
| 6 | 76 |
| 7 | 157 |
| 8 | 324 |
| 9 | 667 |
| 10 | 1375 |
| 11 | 2831 |
| 12 | 5832 |
| 13 | 12013 |
| 14 | 24743 |
| 15 | 50965 |
| 16 | 104976 |
| 17 | 216226 |
| 18 | 445375 |
| 19 | 917370 |
| 20 | 1889568 |
| 21 | 3892070 |
| 22 | 8016758 |
| 23 | 16512655 |
| 24 | 34012224 |
| 25 | 70057261 |
| 26 | 144301645 |
| 27 | 297227788 |
| 28 | 612220032 |
[1,2,4,9,18,37,76,157,324,667,1375,2831,5832, 12013,24743,50965,104976,216226,445375,917370, 1889568,3892070,8016758,16512655,34012224, 70057261,144301645,297227788,612220032] |