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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 20 |
| 4 | 70 |
| 5 | 254 |
| 6 | 936 |
| 7 | 3492 |
| 8 | 13150 |
| 9 | 49882 |
| 10 | 190318 |
| 11 | 729576 |
| 12 | 2807816 |
| 13 | 10841962 |
| 14 | 41983588 |
| 15 | 162973568 |
| 16 | 633994982 |
| 17 | 2471010742 |
| 18 | 9646981054 |
| 19 | 37718873700 |
| 20 | 147676286078 |
| 21 | 578883674722 |
| 22 | 2271704404900 |
| 23 | 8923807316892 |
| 24 | 35087269756344 |
| 25 | 138075819924306 |
[1,2,6,20,70,254,936,3492,13150,49882,190318, 729576,2807816,10841962,41983588,162973568, 633994982,2471010742,9646981054,37718873700, 147676286078,578883674722,2271704404900, 8923807316892,35087269756344,138075819924306] |