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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 9 |
| 3 | 71 |
| 4 | 817 |
| 5 | 11599 |
| 6 | 197881 |
| 7 | 3938087 |
| 8 | 89569761 |
| 9 | 2291869727 |
| 10 | 65159228521 |
| 11 | 2037767466679 |
| 12 | 69521938950289 |
| 13 | 2569515452879855 |
| 14 | 102274007835523161 |
| 15 | 4361566914028222919 |
| 16 | 198403133940750790081 |
| 17 | 9589223805173365594687 |
| 18 | 490729273233730201604809 |
[1,1,9,71,817,11599,197881,3938087,89569761, 2291869727,65159228521,2037767466679, 69521938950289,2569515452879855, 102274007835523161,4361566914028222919, 198403133940750790081,9589223805173365594687, 490729273233730201604809] |