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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 6 |
| 4 | 24 |
| 5 | 60 |
| 6 | 180 |
| 7 | 504 |
| 8 | 1440 |
| 9 | 4104 |
| 10 | 11664 |
| 11 | 33264 |
| 12 | 94608 |
| 13 | 269568 |
| 14 | 767232 |
| 15 | 2185056 |
| 16 | 6220800 |
| 17 | 17713728 |
| 18 | 50435136 |
| 19 | 143607168 |
| 20 | 408893184 |
| 21 | 1164253824 |
| 22 | 3315002112 |
| 23 | 9438882048 |
| 24 | 26875535616 |
| 25 | 76523304960 |
| 26 | 217886505984 |
| 27 | 620393043456 |
| 28 | 1766458865664 |
| 29 | 5029677296640 |
[1,1,4,6,24,60,180,504,1440,4104,11664,33264, 94608,269568,767232,2185056,6220800,17713728, 50435136,143607168,408893184,1164253824, 3315002112,9438882048,26875535616,76523304960, 217886505984,620393043456,1766458865664, 5029677296640] |