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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 8 |
| 4 | 17 |
| 5 | 45 |
| 6 | 104 |
| 7 | 280 |
| 8 | 752 |
| 9 | 2076 |
| 10 | 5947 |
| 11 | 17063 |
| 12 | 50170 |
| 13 | 148048 |
| 14 | 440654 |
| 15 | 1318362 |
| 16 | 3954541 |
| 17 | 11900191 |
| 18 | 35855502 |
| 19 | 108184920 |
| 20 | 326687124 |
| 21 | 987055180 |
| 22 | 2983676881 |
| 23 | 9021446161 |
| 24 | 27283340688 |
| 25 | 82523932704 |
| 26 | 249635724500 |
| 27 | 755206783160 |
[2,4,8,17,45,104,280,752,2076,5947,17063,50170, 148048,440654,1318362,3954541,11900191,35855502, 108184920,326687124,987055180,2983676881, 9021446161,27283340688,82523932704,249635724500, 755206783160] |