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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 10 |
| 3 | 39 |
| 4 | 172 |
| 5 | 827 |
| 6 | 4223 |
| 7 | 22513 |
| 8 | 123906 |
| 9 | 698800 |
| 10 | 4017611 |
| 11 | 23459981 |
| 12 | 138753411 |
| 13 | 829497070 |
| 14 | 5004289494 |
| 15 | 30428025015 |
| 16 | 186279229008 |
| 17 | 1147233165477 |
| 18 | 7102899516394 |
| 19 | 44184059607680 |
| 20 | 276013127801339 |
| 21 | 1730802569428854 |
| 22 | 10890903201239142 |
| 23 | 68745550922693495 |
[1,3,10,39,172,827,4223,22513,123906,698800, 4017611,23459981,138753411,829497070,5004289494, 30428025015,186279229008,1147233165477, 7102899516394,44184059607680,276013127801339, 1730802569428854,10890903201239142, 68745550922693495] |