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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -1 |
| 2 | 0 |
| 3 | -1 |
| 4 | 0 |
| 5 | -2 |
| 6 | 0 |
| 7 | -5 |
| 8 | 0 |
| 9 | -14 |
| 10 | 0 |
| 11 | -42 |
| 12 | 0 |
| 13 | -132 |
| 14 | 0 |
| 15 | -429 |
| 16 | 0 |
| 17 | -1430 |
| 18 | 0 |
| 19 | -4862 |
| 20 | 0 |
| 21 | -16796 |
| 22 | 0 |
| 23 | -58786 |
| 24 | 0 |
| 25 | -208012 |
| 26 | 0 |
| 27 | -742900 |
| 28 | 0 |
| 29 | -2674440 |
| 30 | 0 |
| 31 | -9694845 |
| 32 | 0 |
| 33 | -35357670 |
| 34 | 0 |
| 35 | -129644790 |
| 36 | 0 |
| 37 | -477638700 |
| 38 | 0 |
| 39 | -1767263190 |
| 40 | 0 |
| 41 | -6564120420 |
| 42 | 0 |
| 43 | -24466267020 |
| 44 | 0 |
[1,-1,0,-1,0,-2,0,-5,0,-14,0,-42,0,-132,0,-429,0, -1430,0,-4862,0,-16796,0,-58786,0,-208012,0, -742900,0,-2674440,0,-9694845,0,-35357670,0, -129644790,0,-477638700,0,-1767263190,0, -6564120420,0,-24466267020,0] |