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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 8 |
| 4 | 18 |
| 5 | 38 |
| 6 | 82 |
| 7 | 176 |
| 8 | 378 |
| 9 | 812 |
| 10 | 1744 |
| 11 | 3746 |
| 12 | 8046 |
| 13 | 17282 |
| 14 | 37120 |
| 15 | 79730 |
| 16 | 171252 |
| 17 | 367832 |
| 18 | 790066 |
| 19 | 1696982 |
| 20 | 3644946 |
| 21 | 7828976 |
| 22 | 16815850 |
| 23 | 36118748 |
| 24 | 77579424 |
| 25 | 166632770 |
| 26 | 357910366 |
| 27 | 768755330 |
| 28 | 1651208832 |
| 29 | 3546629858 |
| 30 | 7617802852 |
[2,4,8,18,38,82,176,378,812,1744,3746,8046,17282, 37120,79730,171252,367832,790066,1696982,3644946, 7828976,16815850,36118748,77579424,166632770, 357910366,768755330,1651208832,3546629858, 7617802852] |