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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 34 |
| 3 | 650 |
| 4 | 10500 |
| 5 | 161700 |
| 6 | 2493120 |
| 7 | 39372480 |
| 8 | 644112000 |
| 9 | 10977120000 |
| 10 | 195392736000 |
| 11 | 3636061228800 |
| 12 | 70737918451200 |
| 13 | 1437896940480000 |
| 14 | 30512401920000000 |
| 15 | 675213301002240000 |
| 16 | 15564170478624768000 |
| 17 | 373267990604500992000 |
| 18 | 9302809053765427200000 |
[1,34,650,10500,161700,2493120,39372480,644112000, 10977120000,195392736000,3636061228800, 70737918451200,1437896940480000,30512401920000000, 675213301002240000,15564170478624768000, 373267990604500992000,9302809053765427200000] |