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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | -4 |
| 3 | 15 |
| 4 | -60 |
| 5 | 268 |
| 6 | -1275 |
| 7 | 6322 |
| 8 | -32280 |
| 9 | 168525 |
| 10 | -895272 |
| 11 | 4823088 |
| 12 | -26284036 |
| 13 | 144623580 |
| 14 | -802297080 |
| 15 | 4482108215 |
| 16 | -25193038332 |
| 17 | 142365182220 |
| 18 | -808318895340 |
| 19 | 4608847319040 |
| 20 | -26378042959008 |
| 21 | 151485697164867 |
| 22 | -872650786462376 |
| 23 | 5041141102888080 |
[1,2,-4,15,-60,268,-1275,6322,-32280,168525, -895272,4823088,-26284036,144623580,-802297080, 4482108215,-25193038332,142365182220, -808318895340,4608847319040,-26378042959008, 151485697164867,-872650786462376,5041141102888080] |