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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 16 |
| 3 | 520 |
| 4 | 66560 |
| 5 | 33882400 |
| 6 | 69055283200 |
| 7 | 564153087455360 |
| 8 | 18462510039810703360 |
| 9 | 2418626471936038215754240 |
| 10 | 1267795676362601991645220044800 |
| 11 | 2658560574070850656450883768752998400 |
[1,2,16,520,66560,33882400,69055283200, 564153087455360,18462510039810703360, 2418626471936038215754240, 1267795676362601991645220044800, 2658560574070850656450883768752998400] |