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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 57 |
| 5 | 249 |
| 6 | 1011 |
| 7 | 4263 |
| 8 | 17625 |
| 9 | 73617 |
| 10 | 305859 |
| 11 | 1274271 |
| 12 | 5301273 |
| 13 | 22070985 |
| 14 | 91853427 |
| 15 | 382345719 |
| 16 | 1591372281 |
| 17 | 6623856033 |
| 18 | 27570062595 |
| 19 | 114754829487 |
| 20 | 477640222329 |
| 21 | 1988073910041 |
| 22 | 8274909821043 |
| 23 | 34442484832455 |
[1,3,15,57,249,1011,4263,17625,73617,305859, 1274271,5301273,22070985,91853427,382345719, 1591372281,6623856033,27570062595,114754829487, 477640222329,1988073910041,8274909821043, 34442484832455] |