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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 31 |
| 5 | 267 |
| 6 | 3027 |
| 7 | 42599 |
| 8 | 715191 |
| 9 | 13942995 |
| 10 | 309522515 |
| 11 | 7707841015 |
| 12 | 212783127799 |
| 13 | 6449579387715 |
| 14 | 212939326904131 |
| 15 | 7606688596589431 |
| 16 | 292321288041079671 |
| 17 | 12025358303201356019 |
| 18 | 527265684696785414387 |
[0,1,5,31,267,3027,42599,715191,13942995, 309522515,7707841015,212783127799,6449579387715, 212939326904131,7606688596589431, 292321288041079671,12025358303201356019, 527265684696785414387] |