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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | -1 |
| 4 | -2 |
| 5 | -5 |
| 6 | -10 |
| 7 | -20 |
| 8 | -41 |
| 9 | -86 |
| 10 | -182 |
| 11 | -393 |
| 12 | -853 |
| 13 | -1887 |
| 14 | -4208 |
| 15 | -9445 |
| 16 | -21350 |
| 17 | -48612 |
| 18 | -111307 |
| 19 | -255236 |
| 20 | -590543 |
| 21 | -1362919 |
| 22 | -3182137 |
| 23 | -7362611 |
| 24 | -17377129 |
| 25 | -40125851 |
| 26 | -96106251 |
| 27 | -219681825 |
| 28 | -539266908 |
| 29 | -1200140540 |
[1,0,0,-1,-2,-5,-10,-20,-41,-86,-182,-393,-853, -1887,-4208,-9445,-21350,-48612,-111307,-255236, -590543,-1362919,-3182137,-7362611,-17377129, -40125851,-96106251,-219681825,-539266908, -1200140540] |