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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 22 |
| 4 | 82 |
| 5 | 312 |
| 6 | 1210 |
| 7 | 4752 |
| 8 | 18834 |
| 9 | 75186 |
| 10 | 301868 |
| 11 | 1217664 |
| 12 | 4930918 |
| 13 | 20033432 |
| 14 | 81621456 |
| 15 | 333357656 |
| 16 | 1364395770 |
| 17 | 5594799576 |
| 18 | 22980090870 |
| 19 | 94529049296 |
| 20 | 389367825444 |
| 21 | 1605758772136 |
| 22 | 6629456308464 |
| 23 | 27397510466856 |
| 24 | 113329594803078 |
| 25 | 469183242566016 |
| 26 | 1943927996932656 |
[1,2,6,22,82,312,1210,4752,18834,75186,301868, 1217664,4930918,20033432,81621456,333357656, 1364395770,5594799576,22980090870,94529049296, 389367825444,1605758772136,6629456308464, 27397510466856,113329594803078,469183242566016, 1943927996932656] |