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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 19 |
| 5 | 55 |
| 6 | 200 |
| 7 | 713 |
| 8 | 2740 |
| 9 | 10651 |
| 10 | 42637 |
| 11 | 173012 |
| 12 | 713280 |
| 13 | 2972389 |
| 14 | 12514188 |
| 15 | 53119400 |
| 16 | 227140464 |
| 17 | 977382586 |
| 18 | 4229274235 |
| 19 | 18391269922 |
| 20 | 80330516578 |
| 21 | 352269725526 |
| 22 | 1550357247476 |
| 23 | 6845517553493 |
| 24 | 30316222112019 |
| 25 | 134626183784975 |
| 26 | 599341552234773 |
| 27 | 2674393679352974 |
[1,3,6,19,55,200,713,2740,10651,42637,173012, 713280,2972389,12514188,53119400,227140464, 977382586,4229274235,18391269922,80330516578, 352269725526,1550357247476,6845517553493, 30316222112019,134626183784975,599341552234773, 2674393679352974] |