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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 3 |
| 6 | 5 |
| 7 | 9 |
| 8 | 17 |
| 9 | 30 |
| 10 | 53 |
| 11 | 94 |
| 12 | 169 |
| 13 | 303 |
| 14 | 543 |
| 15 | 968 |
| 16 | 1728 |
| 17 | 3080 |
| 18 | 5491 |
| 19 | 9776 |
| 20 | 17415 |
| 21 | 31008 |
[1,1,1,2,3,5,9,17,30,53,94,169,303,543,968,1728, 3080,5491,9776,17415,31008] |