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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 14 |
| 5 | 72 |
| 6 | 489 |
| 7 | 3722 |
| 8 | 33641 |
| 9 | 334520 |
| 10 | 3761688 |
| 11 | 45898272 |
| 12 | 615641806 |
| 13 | 8863726704 |
| 14 | 137786878644 |
| 15 | 2279658872696 |
| 16 | 40229212948404 |
| 17 | 750433323448128 |
| 18 | 14801457167223872 |
| 19 | 306869893647304896 |
| 20 | 6683254543551623904 |
| 21 | 152281219079726183040 |
| 22 | 3626445842114839589952 |
[1,1,3,14,72,489,3722,33641,334520,3761688, 45898272,615641806,8863726704,137786878644, 2279658872696,40229212948404,750433323448128, 14801457167223872,306869893647304896, 6683254543551623904,152281219079726183040, 3626445842114839589952] |