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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 18 |
| 4 | 270 |
| 5 | 432 |
| 6 | 17010 |
| 7 | 2721600 |
| 8 | 40824 |
| 9 | 1175731200 |
| 10 | 1515591000 |
| 11 | 217275125760 |
| 12 | 354648294000 |
| 13 | 5084237942784000 |
| 14 | 114578679600 |
| 15 | 915162829701120000 |
| 16 | 1595278956070800000 |
| 17 | 298709147614445568000 |
| 18 | 818378104464320400000 |
| 19 | 168561571998831634022400000 |
| 20 | 982053725357184480000 |
| 21 | 45745017385529077294694400000 |
| 22 | 279517041579788632620000000 |
[1,1,3,18,270,432,17010,2721600,40824,1175731200, 1515591000,217275125760,354648294000, 5084237942784000,114578679600,915162829701120000, 1595278956070800000,298709147614445568000, 818378104464320400000,168561571998831634022400000, 982053725357184480000, 45745017385529077294694400000, 279517041579788632620000000] |