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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 8 |
| 4 | 17 |
| 5 | 45 |
| 6 | 103 |
| 7 | 264 |
| 8 | 676 |
| 9 | 1724 |
| 10 | 4501 |
| 11 | 11679 |
| 12 | 30579 |
| 13 | 80180 |
| 14 | 210494 |
| 15 | 553858 |
| 16 | 1457853 |
| 17 | 3840945 |
| 18 | 10124071 |
| 19 | 26693522 |
| 20 | 70402100 |
| 21 | 185706800 |
| 22 | 489925347 |
| 23 | 1292616577 |
| 24 | 3410640207 |
| 25 | 8999588762 |
| 26 | 23747752874 |
| 27 | 62666069376 |
| 28 | 165367179091 |
[2,4,8,17,45,103,264,676,1724,4501,11679,30579, 80180,210494,553858,1457853,3840945,10124071, 26693522,70402100,185706800,489925347,1292616577, 3410640207,8999588762,23747752874,62666069376, 165367179091] |