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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 8 |
| 5 | 15 |
| 6 | 32 |
| 7 | 88 |
| 8 | 209 |
| 9 | 539 |
| 10 | 1403 |
| 11 | 3698 |
| 12 | 9962 |
| 13 | 26447 |
| 14 | 71579 |
| 15 | 196590 |
| 16 | 541473 |
| 17 | 1501720 |
| 18 | 4186566 |
| 19 | 11737617 |
[1,2,4,8,15,32,88,209,539,1403,3698,9962,26447, 71579,196590,541473,1501720,4186566,11737617] |