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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 14 |
| 4 | 52 |
| 5 | 200 |
| 6 | 708 |
| 7 | 2642 |
| 8 | 10000 |
| 9 | 37984 |
| 10 | 144876 |
| 11 | 554120 |
| 12 | 2128672 |
| 13 | 8204180 |
| 14 | 31697564 |
| 15 | 122734614 |
| 16 | 476170124 |
| 17 | 1850664202 |
| 18 | 7204005752 |
| 19 | 28081918548 |
| 20 | 109604285492 |
| 21 | 428278469018 |
| 22 | 1675246478864 |
| 23 | 6559126501510 |
| 24 | 25703606447364 |
[1,4,14,52,200,708,2642,10000,37984,144876,554120, 2128672,8204180,31697564,122734614,476170124, 1850664202,7204005752,28081918548,109604285492, 428278469018,1675246478864,6559126501510, 25703606447364] |