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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 14 |
| 3 | 48 |
| 4 | 162 |
| 5 | 547 |
| 6 | 1842 |
| 7 | 6206 |
| 8 | 20906 |
| 9 | 70438 |
| 10 | 237326 |
| 11 | 799629 |
| 12 | 2694199 |
| 13 | 9077599 |
| 14 | 30585239 |
| 15 | 103051135 |
| 16 | 347211149 |
| 17 | 1169861760 |
| 18 | 3941626163 |
| 19 | 13280557904 |
| 20 | 44746308037 |
| 21 | 150764154490 |
| 22 | 507971076799 |
| 23 | 1711511703373 |
| 24 | 5766612400708 |
| 25 | 19429501132982 |
| 26 | 65464000013233 |
[1,4,14,48,162,547,1842,6206,20906,70438,237326, 799629,2694199,9077599,30585239,103051135, 347211149,1169861760,3941626163,13280557904, 44746308037,150764154490,507971076799, 1711511703373,5766612400708,19429501132982, 65464000013233] |