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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 0 |
| 4 | 6 |
| 5 | 0 |
| 6 | 20 |
| 7 | 0 |
| 8 | 70 |
| 9 | 0 |
| 10 | 252 |
| 11 | 0 |
| 12 | 924 |
| 13 | 0 |
| 14 | 3432 |
| 15 | 0 |
| 16 | 12870 |
| 17 | 0 |
| 18 | 48620 |
| 19 | 0 |
| 20 | 184756 |
| 21 | 0 |
| 22 | 705432 |
| 23 | 0 |
| 24 | 2704156 |
| 25 | 0 |
| 26 | 10400600 |
| 27 | 0 |
| 28 | 40116600 |
| 29 | 0 |
| 30 | 155117520 |
| 31 | 0 |
| 32 | 601080390 |
| 33 | 0 |
| 34 | 2333606220 |
| 35 | 0 |
| 36 | 9075135300 |
| 37 | 0 |
| 38 | 35345263800 |
| 39 | 0 |
| 40 | 137846528820 |
| 41 | 0 |
| 42 | 538257874440 |
| 43 | 0 |
| 44 | 2104098963720 |
| 45 | 0 |
| 46 | 8233430727600 |
| 47 | 0 |
| 48 | 32247603683100 |
| 49 | 0 |
| 50 | 126410606437752 |
| 51 | 0 |
[1,0,2,0,6,0,20,0,70,0,252,0,924,0,3432,0,12870,0, 48620,0,184756,0,705432,0,2704156,0,10400600,0, 40116600,0,155117520,0,601080390,0,2333606220,0, 9075135300,0,35345263800,0,137846528820,0, 538257874440,0,2104098963720,0,8233430727600,0, 32247603683100,0,126410606437752,0] |