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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 14 |
| 4 | 46 |
| 5 | 144 |
| 6 | 540 |
| 7 | 2008 |
| 8 | 7290 |
| 9 | 28134 |
| 10 | 110656 |
| 11 | 428810 |
| 12 | 1693984 |
| 13 | 6849592 |
| 14 | 27500866 |
| 15 | 110897284 |
| 16 | 455131778 |
| 17 | 1867725934 |
| 18 | 7659244962 |
| 19 | 31746858056 |
| 20 | 132117155340 |
| 21 | 549012909864 |
| 22 | 2293962286648 |
| 23 | 9634651916470 |
| 24 | 40448606439588 |
| 25 | 170207330110082 |
| 26 | 719489442018754 |
| 27 | 3044102473742254 |
[1,2,4,14,46,144,540,2008,7290,28134,110656, 428810,1693984,6849592,27500866,110897284, 455131778,1867725934,7659244962,31746858056, 132117155340,549012909864,2293962286648, 9634651916470,40448606439588,170207330110082, 719489442018754,3044102473742254] |