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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 6 |
| 3 | 11 |
| 4 | 24 |
| 5 | 66 |
| 6 | 196 |
| 7 | 576 |
| 8 | 1692 |
| 9 | 5110 |
| 10 | 15933 |
| 11 | 50604 |
| 12 | 161988 |
| 13 | 521700 |
| 14 | 1693362 |
| 15 | 5541679 |
| 16 | 18260055 |
| 17 | 60487659 |
| 18 | 201272437 |
| 19 | 672550158 |
| 20 | 2256204327 |
| 21 | 7596059333 |
| 22 | 25655943417 |
| 23 | 86904524289 |
| 24 | 295154911774 |
| 25 | 1004906765178 |
| 26 | 3429178160346 |
| 27 | 11726499288028 |
| 28 | 40178538608682 |
[1,3,6,11,24,66,196,576,1692,5110,15933,50604, 161988,521700,1693362,5541679,18260055,60487659, 201272437,672550158,2256204327,7596059333, 25655943417,86904524289,295154911774, 1004906765178,3429178160346,11726499288028, 40178538608682] |