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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 6 |
| 4 | 396 |
| 5 | 420000 |
| 6 | 9432450000 |
| 7 | 5571367220160000 |
| 8 | 103458225408290423193600 |
| 9 | 70288262635020872178876253470720 |
| 10 | 1993179010286886206697449779415040000000000 |
| 11 | 2650683735711909138223088071500675703191552000000000000 |
[1,1,6,396,420000,9432450000,5571367220160000, 103458225408290423193600, 70288262635020872178876253470720, 1993179010286886206697449779415040000000000, 26506837357119091382230880715006757031915520000000\ 00000] |