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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 21 |
| 3 | 171 |
| 4 | 1509 |
| 5 | 13995 |
| 6 | 134277 |
| 7 | 1320651 |
| 8 | 13237221 |
| 9 | 134682219 |
| 10 | 1387100229 |
| 11 | 14430764043 |
| 12 | 151415596197 |
| 13 | 1600364733867 |
| 14 | 17022016484613 |
| 15 | 182055719885643 |
| 16 | 1956671540189541 |
| 17 | 21121180251536619 |
| 18 | 228880429935661509 |
| 19 | 2488986535173458571 |
| 20 | 27152943714786745893 |
[1,3,21,171,1509,13995,134277,1320651,13237221, 134682219,1387100229,14430764043,151415596197, 1600364733867,17022016484613,182055719885643, 1956671540189541,21121180251536619, 228880429935661509,2488986535173458571, 27152943714786745893] |