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| n | a(n) |
|---|---|
| 4 | 2 |
| 5 | 28 |
| 6 | 182 |
| 7 | 864 |
| 8 | 3474 |
| 9 | 12660 |
| 10 | 43358 |
| 11 | 142552 |
| 12 | 455930 |
| 13 | 1430796 |
| 14 | 4431078 |
| 15 | 13595664 |
| 16 | 41441570 |
| 17 | 125732836 |
| 18 | 380212142 |
| 19 | 1147057800 |
| 20 | 3454803594 |
| 21 | 10393245180 |
| 22 | 31240551350 |
| 23 | 93849578560 |
| 24 | 281817169202 |
| 25 | 846013542228 |
| 26 | 2539215029502 |
| 27 | 7620094559544 |
| 28 | 22865383949594 |
[2,28,182,864,3474,12660,43358,142552,455930, 1430796,4431078,13595664,41441570,125732836, 380212142,1147057800,3454803594,10393245180, 31240551350,93849578560,281817169202,846013542228, 2539215029502,7620094559544,22865383949594] |