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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 7 |
| 4 | 28 |
| 5 | 54 |
| 6 | 212 |
| 7 | 428 |
| 8 | 1652 |
| 9 | 3410 |
| 10 | 13004 |
| 11 | 27158 |
| 12 | 102740 |
| 13 | 215998 |
| 14 | 812892 |
| 15 | 1715842 |
| 16 | 6435860 |
| 17 | 13618366 |
| 18 | 50970780 |
| 19 | 108022954 |
| 20 | 403751540 |
| 21 | 856522206 |
| 22 | 3198552316 |
| 23 | 6789722794 |
| 24 | 25340854612 |
| 25 | 53813984430 |
| 26 | 200773770908 |
| 27 | 426474521338 |
[1,4,7,28,54,212,428,1652,3410,13004,27158,102740, 215998,812892,1715842,6435860,13618366,50970780, 108022954,403751540,856522206,3198552316, 6789722794,25340854612,53813984430,200773770908, 426474521338] |