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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 20 |
| 4 | 70 |
| 5 | 252 |
| 6 | 924 |
| 7 | 3432 |
| 8 | 12870 |
| 9 | 48620 |
| 10 | 184756 |
| 11 | 705432 |
| 12 | 2704156 |
| 13 | 10400600 |
| 14 | 40116600 |
| 15 | 155117520 |
| 16 | 601080390 |
| 17 | 2333606220 |
| 18 | 9075135300 |
| 19 | 35345263800 |
| 20 | 137846528820 |
| 21 | 538257874440 |
| 22 | 2104098963720 |
| 23 | 8233430727600 |
| 24 | 32247603683100 |
| 25 | 126410606437752 |
| 26 | 495918532948104 |
| 27 | 1946939425648112 |
[1,2,6,20,70,252,924,3432,12870,48620,184756, 705432,2704156,10400600,40116600,155117520, 601080390,2333606220,9075135300,35345263800, 137846528820,538257874440,2104098963720, 8233430727600,32247603683100,126410606437752, 495918532948104,1946939425648112] |