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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 16 |
| 3 | 103 |
| 4 | 735 |
| 5 | 5592 |
| 6 | 44452 |
| 7 | 364815 |
| 8 | 3067558 |
| 9 | 26290517 |
| 10 | 228819168 |
| 11 | 2016953848 |
| 12 | 17968790029 |
| 13 | 161536295244 |
| 14 | 1463535347928 |
| 15 | 13349907110367 |
| 16 | 122499957767130 |
| 17 | 1130001670577730 |
| 18 | 10472708110616136 |
| 19 | 97468774074103041 |
| 20 | 910582642690819351 |
[1,3,16,103,735,5592,44452,364815,3067558, 26290517,228819168,2016953848,17968790029, 161536295244,1463535347928,13349907110367, 122499957767130,1130001670577730, 10472708110616136,97468774074103041, 910582642690819351] |