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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 14 |
| 4 | 105 |
| 5 | 1080 |
| 6 | 13916 |
| 7 | 212634 |
| 8 | 3723198 |
| 9 | 73047825 |
| 10 | 1581256303 |
| 11 | 37350588290 |
| 12 | 954796686233 |
| 13 | 26246234745486 |
| 14 | 771853099673490 |
| 15 | 24180166328032252 |
| 16 | 803996438505301917 |
| 17 | 28283254774663359546 |
| 18 | 1049653570430645994556 |
[1,1,3,14,105,1080,13916,212634,3723198,73047825, 1581256303,37350588290,954796686233, 26246234745486,771853099673490,24180166328032252, 803996438505301917,28283254774663359546, 1049653570430645994556] |