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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 8 |
| 4 | 20 |
| 5 | 48 |
| 6 | 121 |
| 7 | 312 |
| 8 | 820 |
| 9 | 2186 |
| 10 | 5904 |
| 11 | 16104 |
| 12 | 44286 |
| 13 | 122640 |
| 14 | 341640 |
| 15 | 956593 |
| 16 | 2690420 |
| 17 | 7596480 |
| 18 | 21523360 |
| 19 | 61171656 |
| 20 | 174339220 |
| 21 | 498112057 |
| 22 | 1426411800 |
| 23 | 4093181688 |
| 24 | 11767897353 |
| 25 | 33891544377 |
| 26 | 97764070320 |
| 27 | 282429536480 |
| 28 | 817028301962 |
| 29 | 2366564736720 |
[2,4,8,20,48,121,312,820,2186,5904,16104,44286, 122640,341640,956593,2690420,7596480,21523360, 61171656,174339220,498112057,1426411800, 4093181688,11767897353,33891544377,97764070320, 282429536480,817028301962,2366564736720] |