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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 8 |
| 4 | 16 |
| 5 | 224 |
| 6 | 1328 |
| 7 | 8280 |
| 8 | 192960 |
| 9 | 337992 |
| 10 | 33969672 |
| 11 | 11690832 |
| 12 | 7909754400 |
| 13 | -2553028752 |
| 14 | 2357881048560 |
| 15 | 3942533549568 |
| 16 | 661635400722048 |
| 17 | 13397372969553792 |
| 18 | -107825500036658304 |
| 19 | 22964754191590789632 |
| 20 | -572404186520543904768 |
| 21 | 31472786179436211417600 |
| 22 | -886973046496642227294720 |
[1,1,1,8,16,224,1328,8280,192960,337992,33969672, 11690832,7909754400,-2553028752,2357881048560, 3942533549568,661635400722048,13397372969553792, -107825500036658304,22964754191590789632, -572404186520543904768,31472786179436211417600, -886973046496642227294720] |