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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 21 |
| 4 | 166 |
| 5 | 2277 |
| 6 | 49901 |
| 7 | 1675904 |
| 8 | 84239935 |
| 9 | 6231045077 |
| 10 | 668949067432 |
| 11 | 103005162942955 |
| 12 | 22511886374045653 |
| 13 | 6918461813753405930 |
| 14 | 2965189776573865320121 |
| 15 | 1759287329824925168339697 |
| 16 | 1435531006280642249195752862 |
| 17 | 1601571709194974043628781397985 |
| 18 | 2430449338115875591262479128994073 |
[1,2,5,21,166,2277,49901,1675904,84239935, 6231045077,668949067432,103005162942955, 22511886374045653,6918461813753405930, 2965189776573865320121,1759287329824925168339697, 1435531006280642249195752862, 1601571709194974043628781397985, 2430449338115875591262479128994073] |