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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 9 |
| 4 | 378 |
| 5 | 37830 |
| 6 | 3403815 |
| 7 | 290684541 |
| 8 | 23648592268 |
| 9 | 2009304033948 |
| 10 | 165069279069345 |
| 11 | 12108533607540535 |
| 12 | 813240975212887518 |
| 13 | 51447280837022648370 |
| 14 | 3118521194576489150631 |
| 15 | 182797738828031587273965 |
[1,9,378,37830,3403815,290684541,23648592268, 2009304033948,165069279069345,12108533607540535, 813240975212887518,51447280837022648370, 3118521194576489150631,182797738828031587273965] |