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| n | a(n) |
|---|---|
| 5 | 1 |
| 6 | 45 |
| 7 | 1540 |
| 8 | 49840 |
| 9 | 1632099 |
| 10 | 55545735 |
| 11 | 1987186025 |
| 12 | 75078221130 |
| 13 | 2999597292406 |
| 14 | 126693681294180 |
| 15 | 5650573288138415 |
| 16 | 265702055516788800 |
| 17 | 13149171975158028874 |
| 18 | 683615652343279677360 |
| 19 | 37269087381803600233878 |
| 20 | 2126880663709734887508320 |
| 21 | 126841125623724152774643951 |
[1,45,1540,49840,1632099,55545735,1987186025, 75078221130,2999597292406,126693681294180, 5650573288138415,265702055516788800, 13149171975158028874,683615652343279677360, 37269087381803600233878,2126880663709734887508320, 126841125623724152774643951] |