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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 2 |
| 3 | 2 |
| 4 | 6 |
| 5 | 10 |
| 6 | 26 |
| 7 | 66 |
| 8 | 174 |
| 9 | 442 |
| 10 | 1202 |
| 11 | 3298 |
| 12 | 9166 |
| 13 | 25674 |
| 14 | 72810 |
| 15 | 206826 |
| 16 | 595150 |
| 17 | 1712634 |
| 18 | 4978458 |
| 19 | 14494130 |
| 20 | 42502030 |
| 21 | 124660402 |
| 22 | 368221002 |
| 23 | 1087321354 |
| 24 | 3229266742 |
| 25 | 9591013738 |
| 26 | 28624735962 |
| 27 | 85404444970 |
[2,2,2,6,10,26,66,174,442,1202,3298,9166,25674, 72810,206826,595150,1712634,4978458,14494130, 42502030,124660402,368221002,1087321354, 3229266742,9591013738,28624735962,85404444970] |