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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 13 |
| 3 | 65 |
| 4 | 351 |
| 5 | 1989 |
| 6 | 11650 |
| 7 | 69903 |
| 8 | 427225 |
| 9 | 2649229 |
| 10 | 16622079 |
| 11 | 105310673 |
| 12 | 672687322 |
| 13 | 4327037010 |
| 14 | 28002409452 |
| 15 | 182179075689 |
| 16 | 1190778886791 |
| 17 | 7815755146095 |
| 18 | 51491064226095 |
| 19 | 340374137775879 |
| 20 | 2256891800364421 |
| 21 | 15006481967365535 |
| 22 | 100037043223408890 |
[1,3,13,65,351,1989,11650,69903,427225,2649229, 16622079,105310673,672687322,4327037010, 28002409452,182179075689,1190778886791, 7815755146095,51491064226095,340374137775879, 2256891800364421,15006481967365535, 100037043223408890] |