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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 19 |
| 6 | 11 |
| 7 | 321 |
| 8 | -720 |
| 9 | 12489 |
| 10 | -84849 |
| 11 | 1008765 |
| 12 | -10502700 |
| 13 | 131502669 |
| 14 | -1702662077 |
| 15 | 24172986033 |
| 16 | -364322094976 |
| 17 | 5871664124881 |
| 18 | -100335623138817 |
| 19 | 1815293290581909 |
| 20 | -34642054850289196 |
| 21 | 695636985512560149 |
[0,1,1,2,4,19,11,321,-720,12489,-84849,1008765, -10502700,131502669,-1702662077,24172986033, -364322094976,5871664124881,-100335623138817, 1815293290581909,-34642054850289196, 695636985512560149] |