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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 1 |
| 4 | 0 |
| 5 | 21 |
| 6 | 88 |
| 7 | -27 |
| 8 | -704 |
| 9 | 6121 |
| 10 | 50464 |
| 11 | -153559 |
| 12 | -2089216 |
| 13 | 13064637 |
| 14 | 173223040 |
| 15 | -996722035 |
| 16 | -16120801280 |
| 17 | 114653539281 |
| 18 | 2032098365952 |
| 19 | -15657589156655 |
| 20 | -311227464130560 |
| 21 | 2678537704263781 |
| 22 | 58380271774087168 |
[0,1,2,1,0,21,88,-27,-704,6121,50464,-153559, -2089216,13064637,173223040,-996722035, -16120801280,114653539281,2032098365952, -15657589156655,-311227464130560,2678537704263781, 58380271774087168] |