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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 58 |
| 5 | 320 |
| 6 | 1954 |
| 7 | 12961 |
| 8 | 92237 |
| 9 | 698111 |
| 10 | 5583319 |
| 11 | 46952892 |
| 12 | 413560076 |
| 13 | 3803165348 |
| 14 | 36419879176 |
| 15 | 362366133696 |
| 16 | 3738804161990 |
| 17 | 39935163833132 |
| 18 | 440917642476858 |
| 19 | 5025099681646374 |
| 20 | 59044001774803872 |
| 21 | 714419979588724854 |
[1,1,3,12,58,320,1954,12961,92237,698111,5583319, 46952892,413560076,3803165348,36419879176, 362366133696,3738804161990,39935163833132, 440917642476858,5025099681646374, 59044001774803872,714419979588724854] |