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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 1 |
| 4 | 12 |
| 5 | 148 |
| 6 | 3150 |
| 7 | 90075 |
| 8 | 3431015 |
| 9 | 167013000 |
| 10 | 10129020300 |
| 11 | 748997001900 |
| 12 | 66348135107100 |
| 13 | 6937184077639200 |
| 14 | 845432117761631400 |
| 15 | 118799216331711715800 |
| 16 | 19067817942959809023000 |
| 17 | 3467025016814436877800000 |
| 18 | 708946631468824853456352000 |
| 19 | 161976071967463107761759352000 |
[1,1,12,148,3150,90075,3431015,167013000, 10129020300,748997001900,66348135107100, 6937184077639200,845432117761631400, 118799216331711715800,19067817942959809023000, 3467025016814436877800000, 708946631468824853456352000, 161976071967463107761759352000] |