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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 25 |
| 4 | 112 |
| 5 | 557 |
| 6 | 2914 |
| 7 | 15837 |
| 8 | 88531 |
| 9 | 505581 |
| 10 | 2936676 |
| 11 | 17294352 |
| 12 | 103018292 |
| 13 | 619595991 |
| 14 | 3757342674 |
| 15 | 22948207189 |
| 16 | 141033508661 |
| 17 | 871527612640 |
| 18 | 5412015056754 |
| 19 | 33754524947592 |
| 20 | 211353845133650 |
| 21 | 1328099943458743 |
| 22 | 8372466442163468 |
| 23 | 52936608451071755 |
[1,2,6,25,112,557,2914,15837,88531,505581,2936676, 17294352,103018292,619595991,3757342674, 22948207189,141033508661,871527612640, 5412015056754,33754524947592,211353845133650, 1328099943458743,8372466442163468, 52936608451071755] |