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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | -1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 17 |
| 6 | -1 |
| 7 | 271 |
| 8 | 1 |
| 9 | 7937 |
| 10 | -1 |
| 11 | 353791 |
| 12 | 1 |
| 13 | 22368257 |
| 14 | -1 |
| 15 | 1903757311 |
| 16 | 1 |
| 17 | 209865342977 |
| 18 | -1 |
| 19 | 29088885112831 |
| 20 | 1 |
| 21 | 4951498053124097 |
| 22 | -1 |
| 23 | 1015423886506852351 |
| 24 | 1 |
| 25 | 246921480190207983617 |
| 26 | -1 |
| 27 | 70251601603943959887871 |
| 28 | 1 |
| 29 | 23119184187809597841473537 |
[1,2,-1,1,1,17,-1,271,1,7937,-1,353791,1,22368257, -1,1903757311,1,209865342977,-1,29088885112831,1, 4951498053124097,-1,1015423886506852351,1, 246921480190207983617,-1,70251601603943959887871, 1,23119184187809597841473537] |