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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 42 |
| 4 | 764 |
| 5 | 20400 |
| 6 | 731862 |
| 7 | 33397168 |
| 8 | 1867950856 |
| 9 | 124680486816 |
| 10 | 9733666171850 |
| 11 | 874978919826264 |
| 12 | 89437471672859532 |
| 13 | 10289414670501314608 |
| 14 | 1320997962702267801070 |
| 15 | 187894667581541881127640 |
| 16 | 29426125555003596239544848 |
| 17 | 5046809953516305090792395328 |
[1,4,42,764,20400,731862,33397168,1867950856, 124680486816,9733666171850,874978919826264, 89437471672859532,10289414670501314608, 1320997962702267801070,187894667581541881127640, 29426125555003596239544848, 5046809953516305090792395328] |