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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | -2 |
| 4 | -6 |
| 5 | -18 |
| 6 | -54 |
| 7 | -168 |
| 8 | -534 |
| 9 | -1732 |
| 10 | -5706 |
| 11 | -19038 |
| 12 | -64176 |
| 13 | -218190 |
| 14 | -747180 |
| 15 | -2574488 |
| 16 | -8918070 |
| 17 | -31036560 |
| 18 | -108457488 |
| 19 | -380390574 |
| 20 | -1338495492 |
| 21 | -4723664566 |
| 22 | -16714545822 |
| 23 | -59286878556 |
| 24 | -210755970528 |
| 25 | -750721297056 |
| 26 | -2679075662922 |
| 27 | -9577156141654 |
| 28 | -34290858526926 |
| 29 | -122959225609518 |
[1,0,0,-2,-6,-18,-54,-168,-534,-1732,-5706,-19038, -64176,-218190,-747180,-2574488,-8918070, -31036560,-108457488,-380390574,-1338495492, -4723664566,-16714545822,-59286878556, -210755970528,-750721297056,-2679075662922, -9577156141654,-34290858526926,-122959225609518] |