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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 15 |
| 2 | 141 |
| 3 | 1275 |
| 4 | 11481 |
| 5 | 103335 |
| 6 | 930021 |
| 7 | 8370195 |
| 8 | 75331761 |
| 9 | 677985855 |
| 10 | 6101872701 |
| 11 | 54916854315 |
| 12 | 494251688841 |
| 13 | 4448265199575 |
| 14 | 40034386796181 |
| 15 | 360309481165635 |
| 16 | 3242785330490721 |
| 17 | 29185067974416495 |
| 18 | 262665611769748461 |
[1,15,141,1275,11481,103335,930021,8370195, 75331761,677985855,6101872701,54916854315, 494251688841,4448265199575,40034386796181, 360309481165635,3242785330490721, 29185067974416495,262665611769748461] |