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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 217 |
| 5 | 31 |
| 6 | 3937 |
| 7 | 127 |
| 8 | 57337 |
| 9 | 253921 |
| 10 | 917497 |
| 11 | 3670009 |
| 12 | 16252897 |
| 13 | 8191 |
| 14 | 61079603913818329 |
| 15 | 1073602561 |
| 16 | 4294434817 |
| 17 | 131071 |
| 18 | 66571993057 |
| 19 | 524287 |
| 20 | 1208766717309082486038529 |
| 21 | 9222228542614937599 |
| 22 | 17590038552577 |
| 23 | 500367932999371587367 |
| 24 | 281472829095937 |
| 25 | 1125897758834689 |
[1,3,7,217,31,3937,127,57337,253921,917497, 3670009,16252897,8191,61079603913818329, 1073602561,4294434817,131071,66571993057,524287, 1208766717309082486038529,9222228542614937599, 17590038552577,500367932999371587367, 281472829095937,1125897758834689] |