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| n | a(n) |
|---|---|
| 0 | -1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 15 |
| 4 | 25 |
| 5 | 49 |
| 6 | 97 |
| 7 | 181 |
| 8 | 433 |
| 9 | 819 |
| 10 | 1541 |
| 11 | 3147 |
| 12 | 6271 |
| 13 | 12469 |
| 14 | 25087 |
| 15 | 49455 |
| 16 | 99255 |
| 17 | 196057 |
| 18 | 391815 |
| 19 | 781893 |
| 20 | 1555935 |
| 21 | 3106511 |
| 22 | 6191001 |
| 23 | 12351963 |
| 24 | 24658715 |
| 25 | 49173803 |
| 26 | 98136735 |
| 27 | 195868789 |
| 28 | 391110307 |
| 29 | 780774507 |
| 30 | 1559147549 |
| 31 | 3113261723 |
| 32 | 6218243597 |
| 33 | 12419791799 |
| 34 | 24808942497 |
[-1,1,5,15,25,49,97,181,433,819,1541,3147,6271, 12469,25087,49455,99255,196057,391815,781893, 1555935,3106511,6191001,12351963,24658715, 49173803,98136735,195868789,391110307,780774507, 1559147549,3113261723,6218243597,12419791799, 24808942497] |