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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 10 |
| 5 | 28 |
| 6 | 84 |
| 7 | 260 |
| 8 | 816 |
| 9 | 2576 |
| 10 | 8152 |
| 11 | 25824 |
| 12 | 81840 |
| 13 | 259408 |
| 14 | 822304 |
| 15 | 2606720 |
| 16 | 8263456 |
| 17 | 26195776 |
| 18 | 83042752 |
| 19 | 263252544 |
| 20 | 834533120 |
| 21 | 2645541888 |
| 22 | 8386596224 |
| 23 | 26586234880 |
| 24 | 84280663296 |
| 25 | 267176990976 |
| 26 | 846974167552 |
| 27 | 2684981361664 |
[1,2,4,10,28,84,260,816,2576,8152,25824,81840, 259408,822304,2606720,8263456,26195776,83042752, 263252544,834533120,2645541888,8386596224, 26586234880,84280663296,267176990976,846974167552, 2684981361664] |