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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 13 |
| 3 | 64 |
| 4 | 287 |
| 5 | 1515 |
| 6 | 8143 |
| 7 | 46030 |
| 8 | 265909 |
| 9 | 1572193 |
| 10 | 9443997 |
| 11 | 57529101 |
| 12 | 354394057 |
| 13 | 2204333079 |
| 14 | 13823770729 |
| 15 | 87311462772 |
| 16 | 554904606279 |
| 17 | 3546103422655 |
| 18 | 22772157825695 |
| 19 | 146876986425311 |
| 20 | 951065019090195 |
[1,6,13,64,287,1515,8143,46030,265909,1572193, 9443997,57529101,354394057,2204333079,13823770729, 87311462772,554904606279,3546103422655, 22772157825695,146876986425311,951065019090195] |