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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 20 |
| 4 | 62 |
| 5 | 194 |
| 6 | 610 |
| 7 | 1914 |
| 8 | 6006 |
| 9 | 18850 |
| 10 | 59158 |
| 11 | 185658 |
| 12 | 582662 |
| 13 | 1828602 |
| 14 | 5738806 |
| 15 | 18010426 |
| 16 | 56523158 |
| 17 | 177389882 |
| 18 | 556712886 |
| 19 | 1747164122 |
| 20 | 5483225814 |
| 21 | 17208323450 |
| 22 | 54005872822 |
| 23 | 169489741850 |
| 24 | 531919420822 |
| 25 | 1669353361210 |
[1,2,6,20,62,194,610,1914,6006,18850,59158,185658, 582662,1828602,5738806,18010426,56523158, 177389882,556712886,1747164122,5483225814, 17208323450,54005872822,169489741850,531919420822, 1669353361210] |