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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 80 |
| 4 | 1900 |
| 5 | 55490 |
| 6 | 1848660 |
| 7 | 67630080 |
| 8 | 2657251005 |
| 9 | 110560510400 |
| 10 | 4824793769260 |
| 11 | 219334788340040 |
| 12 | 10334817935549420 |
| 13 | 502814686712631520 |
| 14 | 25184673137026274600 |
| 15 | 1295595210394570426800 |
| 16 | 68326193725188929358600 |
| 17 | 3688253200687778850553800 |
| 18 | 203524353764195058692833200 |
| 19 | 11468618360097679305600299400 |
| 20 | 659345494779348103800864088800 |
| 21 | 38644445208422874351089132287200 |
[1,5,80,1900,55490,1848660,67630080,2657251005, 110560510400,4824793769260,219334788340040, 10334817935549420,502814686712631520, 25184673137026274600,1295595210394570426800, 68326193725188929358600,3688253200687778850553800, 203524353764195058692833200, 11468618360097679305600299400, 659345494779348103800864088800, 38644445208422874351089132287200] |