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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 0 |
| 3 | -1 |
| 4 | 12 |
| 5 | -34 |
| 6 | 120 |
| 7 | 146 |
| 8 | -2352 |
| 9 | 23848 |
| 10 | -53280 |
| 11 | -371768 |
| 12 | 12223200 |
| 13 | -107535440 |
| 14 | 706340544 |
| 15 | 2599870352 |
| 16 | -95898673920 |
| 17 | 1486560431744 |
| 18 | -8308014488064 |
| 19 | -67260673442176 |
| 20 | 3505513923832320 |
| 21 | -54539552924497664 |
| 22 | 499029405102412800 |
[0,1,0,-1,12,-34,120,146,-2352,23848,-53280, -371768,12223200,-107535440,706340544,2599870352, -95898673920,1486560431744,-8308014488064, -67260673442176,3505513923832320, -54539552924497664,499029405102412800] |