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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 2 |
| 3 | 2 |
| 4 | 17 |
| 5 | 31 |
| 6 | 971 |
| 7 | 127 |
| 8 | 856073 |
| 9 | 19427 |
| 10 | 58537 |
| 11 | 176123 |
| 12 | 529393 |
| 13 | 8191 |
| 14 | 128467258961 |
| 15 | 977123207545039 |
| 16 | 43013953 |
| 17 | 131071 |
| 18 | 3814697134553 |
| 19 | 524287 |
| 20 | 79792266297087713 |
[2,2,2,17,31,971,127,856073,19427,58537,176123, 529393,8191,128467258961,977123207545039,43013953, 131071,3814697134553,524287,79792266297087713] |