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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 16 |
| 5 | 47 |
| 6 | 146 |
| 7 | 471 |
| 8 | 1562 |
| 9 | 5291 |
| 10 | 18226 |
| 11 | 63648 |
| 12 | 224808 |
| 13 | 801686 |
| 14 | 2882452 |
| 15 | 10437745 |
| 16 | 38032110 |
| 17 | 139339635 |
| 18 | 512996370 |
| 19 | 1896907980 |
| 20 | 7041759120 |
| 21 | 26233530210 |
| 22 | 98046684060 |
| 23 | 367525880670 |
| 24 | 1381386710964 |
| 25 | 5205006015102 |
[1,1,2,6,16,47,146,471,1562,5291,18226,63648, 224808,801686,2882452,10437745,38032110,139339635, 512996370,1896907980,7041759120,26233530210, 98046684060,367525880670,1381386710964, 5205006015102] |