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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 55 |
| 4 | 631 |
| 5 | 8001 |
| 6 | 130453 |
| 7 | 2323483 |
| 8 | 48916087 |
| 9 | 1129559068 |
| 10 | 29442232007 |
| 11 | 835245785452 |
| 12 | 26113646252773 |
| 13 | 880685234758941 |
| 14 | 32191922753658129 |
| 15 | 1259701078978200555 |
| 16 | 52802268925363689079 |
| 17 | 2352843030410455053891 |
| 18 | 111343906794849929711260 |
| 19 | 5567596199767400904172045 |
[1,1,7,55,631,8001,130453,2323483,48916087, 1129559068,29442232007,835245785452, 26113646252773,880685234758941,32191922753658129, 1259701078978200555,52802268925363689079, 2352843030410455053891,111343906794849929711260, 5567596199767400904172045] |