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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 20 |
| 4 | 65 |
| 5 | 203 |
| 6 | 648 |
| 7 | 2057 |
| 8 | 6527 |
| 9 | 20740 |
| 10 | 65833 |
| 11 | 209091 |
| 12 | 663912 |
| 13 | 2108281 |
| 14 | 6694767 |
| 15 | 21258988 |
| 16 | 67507481 |
| 17 | 214367707 |
| 18 | 680719048 |
| 19 | 2161603009 |
| 20 | 6864108879 |
| 21 | 21796779780 |
| 22 | 69215046289 |
| 23 | 219790389515 |
| 24 | 697938050920 |
| 25 | 2216282199881 |
| 26 | 7037740324047 |
[1,7,20,65,203,648,2057,6527,20740,65833,209091, 663912,2108281,6694767,21258988,67507481, 214367707,680719048,2161603009,6864108879, 21796779780,69215046289,219790389515,697938050920, 2216282199881,7037740324047] |