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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 28 |
| 3 | 98 |
| 4 | 270 |
| 5 | 676 |
| 6 | 1588 |
| 7 | 3604 |
| 8 | 7960 |
| 9 | 17254 |
| 10 | 36848 |
| 11 | 77776 |
| 12 | 162610 |
| 13 | 337292 |
| 14 | 694982 |
| 15 | 1423852 |
| 16 | 2902806 |
| 17 | 5892558 |
| 18 | 11916410 |
| 19 | 24017514 |
| 20 | 48262212 |
| 21 | 96719706 |
| 22 | 193358890 |
| 23 | 385702166 |
| 24 | 767826768 |
| 25 | 1525708160 |
| 26 | 3026506470 |
| 27 | 5994196442 |
| 28 | 11854696726 |
[2,28,98,270,676,1588,3604,7960,17254,36848,77776, 162610,337292,694982,1423852,2902806,5892558, 11916410,24017514,48262212,96719706,193358890, 385702166,767826768,1525708160,3026506470, 5994196442,11854696726] |