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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 42 |
| 4 | 2472 |
| 5 | 295320 |
| 6 | 61369920 |
| 7 | 20250513360 |
| 8 | 9970976453760 |
| 9 | 6994020967113600 |
| 10 | 6738118625057702400 |
| 11 | 8654627604114610272000 |
| 12 | 14457770976132703296000000 |
| 13 | 30761772133454776218220416000 |
| 14 | 81885712959925376996901780172800 |
| 15 | 268520193454950330194198952198144000 |
[1,1,2,42,2472,295320,61369920,20250513360, 9970976453760,6994020967113600, 6738118625057702400,8654627604114610272000, 14457770976132703296000000, 30761772133454776218220416000, 81885712959925376996901780172800, 268520193454950330194198952198144000] |