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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 42 |
| 3 | 546 |
| 4 | 6552 |
| 5 | 78120 |
| 6 | 959760 |
| 7 | 12353040 |
| 8 | 167771520 |
| 9 | 2410611840 |
| 10 | 36654508800 |
| 11 | 589291718400 |
| 12 | 10002032409600 |
| 13 | 178908534604800 |
| 14 | 3366215358105600 |
| 15 | 66496549287168000 |
| 16 | 1376573115101184000 |
| 17 | 29810519036153856000 |
| 18 | 674176353586864128000 |
| 19 | 15896946656727392256000 |
[1,3,42,546,6552,78120,959760,12353040,167771520, 2410611840,36654508800,589291718400, 10002032409600,178908534604800,3366215358105600, 66496549287168000,1376573115101184000, 29810519036153856000,674176353586864128000, 15896946656727392256000] |