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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 3 |
| 3 | 15 |
| 4 | 20 |
| 5 | 51 |
| 6 | 68 |
| 7 | 255 |
| 8 | 340 |
| 9 | 771 |
| 10 | 1028 |
| 11 | 3855 |
| 12 | 5140 |
| 13 | 13107 |
| 14 | 17476 |
| 15 | 65535 |
| 16 | 87380 |
| 17 | 196611 |
| 18 | 262148 |
| 19 | 983055 |
[2,3,15,20,51,68,255,340,771,1028,3855,5140,13107, 17476,65535,87380,196611,262148,983055] |