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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 5 |
| 4 | -12 |
| 5 | 49 |
| 6 | -225 |
| 7 | 1133 |
| 8 | -8176 |
| 9 | 61665 |
| 10 | -567225 |
| 11 | 5701365 |
| 12 | -62634924 |
| 13 | 755601105 |
| 14 | -9768453513 |
| 15 | 136547354973 |
| 16 | -2041147352640 |
| 17 | 32565339301569 |
| 18 | -552510593169489 |
| 19 | 9924462641102181 |
| 20 | -188278493388946860 |
| 21 | 3759992000006225265 |
[0,1,-1,5,-12,49,-225,1133,-8176,61665,-567225, 5701365,-62634924,755601105,-9768453513, 136547354973,-2041147352640,32565339301569, -552510593169489,9924462641102181, -188278493388946860,3759992000006225265] |