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| n | a(n) |
|---|---|
| 1 | 9 |
| 2 | 81 |
| 3 | 323 |
| 4 | 1360 |
| 5 | 6525 |
| 6 | 32393 |
| 7 | 165626 |
| 8 | 855471 |
| 9 | 4449491 |
| 10 | 23211486 |
| 11 | 121314285 |
| 12 | 634633939 |
| 13 | 3321850282 |
| 14 | 17392770603 |
| 15 | 91082814851 |
| 16 | 477033173168 |
| 17 | 2498544485965 |
| 18 | 13087020633451 |
| 19 | 68549369291830 |
| 20 | 359063591740895 |
| 21 | 1880798904630019 |
[9,81,323,1360,6525,32393,165626,855471,4449491, 23211486,121314285,634633939,3321850282, 17392770603,91082814851,477033173168, 2498544485965,13087020633451,68549369291830, 359063591740895,1880798904630019] |