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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 13 |
| 5 | 69 |
| 6 | 396 |
| 7 | 2355 |
| 8 | 14363 |
| 9 | 89706 |
| 10 | 573828 |
| 11 | 3758866 |
| 12 | 25195016 |
| 13 | 172591294 |
| 14 | 1206482317 |
| 15 | 8592827996 |
| 16 | 62257890162 |
| 17 | 458214977642 |
| 18 | 3421294482237 |
| 19 | 25884913987768 |
| 20 | 198236423171483 |
| 21 | 1535315006313002 |
| 22 | 12015208271571543 |
| 23 | 94943908405295171 |
| 24 | 757044806198966152 |
[1,1,1,3,13,69,396,2355,14363,89706,573828, 3758866,25195016,172591294,1206482317,8592827996, 62257890162,458214977642,3421294482237, 25884913987768,198236423171483,1535315006313002, 12015208271571543,94943908405295171, 757044806198966152] |