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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 1 |
| 7 | 210 |
| 8 | 56 |
| 9 | 504 |
| 10 | 1260 |
| 11 | 9240 |
| 12 | 166320 |
| 13 | 360360 |
| 14 | 5045040 |
| 15 | 75675600 |
| 16 | 1210809600 |
| 17 | 4084080 |
| 18 | 73513440 |
| 19 | 698377680 |
| 20 | 13967553600 |
| 21 | 146659312800 |
| 22 | 1075501627200 |
| 23 | 37104806138400 |
| 24 | 296838449107200 |
| 25 | 7420961227680000 |
| 26 | 96472495959840000 |
| 27 | 2604757390915680000 |
[1,1,1,1,1,1,1,210,56,504,1260,9240,166320,360360, 5045040,75675600,1210809600,4084080,73513440, 698377680,13967553600,146659312800,1075501627200, 37104806138400,296838449107200,7420961227680000, 96472495959840000,2604757390915680000] |