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| n | a(n) |
|---|---|
| 1 | 8 |
| 2 | 18 |
| 3 | 42 |
| 4 | 90 |
| 5 | 192 |
| 6 | 394 |
| 7 | 806 |
| 8 | 1618 |
| 9 | 3244 |
| 10 | 6444 |
| 11 | 12798 |
| 12 | 25306 |
| 13 | 50056 |
| 14 | 98830 |
| 15 | 195252 |
| 16 | 385546 |
| 17 | 761880 |
| 18 | 1505776 |
| 19 | 2978372 |
| 20 | 5893812 |
| 21 | 11672100 |
| 22 | 23128778 |
| 23 | 45863610 |
| 24 | 91000330 |
| 25 | 180675314 |
| 26 | 358921836 |
| 27 | 713425574 |
| 28 | 1418791694 |
| 29 | 2822950098 |
| 30 | 5619290544 |
[8,18,42,90,192,394,806,1618,3244,6444,12798, 25306,50056,98830,195252,385546,761880,1505776, 2978372,5893812,11672100,23128778,45863610, 91000330,180675314,358921836,713425574,1418791694, 2822950098,5619290544] |