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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 4 |
| 2 | 11 |
| 3 | 32 |
| 4 | 93 |
| 5 | 270 |
| 6 | 787 |
| 7 | 2308 |
| 8 | 6809 |
| 9 | 20186 |
| 10 | 60063 |
| 11 | 179184 |
| 12 | 535525 |
| 13 | 1602502 |
| 14 | 4799339 |
| 15 | 14381660 |
| 16 | 43112241 |
| 17 | 129271218 |
| 18 | 387682615 |
| 19 | 1162785736 |
| 20 | 3487832957 |
| 21 | 10462450334 |
| 22 | 31385253891 |
| 23 | 94151567412 |
| 24 | 282446313673 |
| 25 | 847322163850 |
[2,4,11,32,93,270,787,2308,6809,20186,60063, 179184,535525,1602502,4799339,14381660,43112241, 129271218,387682615,1162785736,3487832957, 10462450334,31385253891,94151567412,282446313673, 847322163850] |