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| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 11 |
| 3 | 55 |
| 4 | 263 |
| 5 | 1248 |
| 6 | 5959 |
| 7 | 28399 |
| 8 | 135383 |
| 9 | 645407 |
| 10 | 3076736 |
| 11 | 14667339 |
| 12 | 69921635 |
| 13 | 333328023 |
| 14 | 1589030151 |
| 15 | 7575170720 |
| 16 | 36112097743 |
| 17 | 172152371303 |
| 18 | 820678962999 |
| 19 | 3912313001599 |
| 20 | 18650646247168 |
| 21 | 88910730122387 |
| 22 | 423852226145531 |
[3,11,55,263,1248,5959,28399,135383,645407, 3076736,14667339,69921635,333328023,1589030151, 7575170720,36112097743,172152371303,820678962999, 3912313001599,18650646247168,88910730122387, 423852226145531] |