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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 73 |
| 4 | 1031 |
| 5 | 18501 |
| 6 | 403495 |
| 7 | 10366833 |
| 8 | 306717703 |
| 9 | 10271072557 |
| 10 | 384058268507 |
| 11 | 15861842372465 |
| 12 | 717135437119271 |
| 13 | 35228475333207937 |
| 14 | 1868440035684996207 |
| 15 | 106412817671933423073 |
| 16 | 6477200889282232394759 |
| 17 | 419626639092214594301373 |
| 18 | 28829330550533269570699411 |
[1,1,7,73,1031,18501,403495,10366833,306717703, 10271072557,384058268507,15861842372465, 717135437119271,35228475333207937, 1868440035684996207,106412817671933423073, 6477200889282232394759,419626639092214594301373, 28829330550533269570699411] |