The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 120 |
| 3 | 600 |
| 4 | 600 |
| 5 | 200 |
| 6 | 25 |
| 7 | 1 |
| 8 | 14400 |
| 9 | 504000 |
| 10 | 2664000 |
| 11 | 4608000 |
| 12 | 3501000 |
| 13 | 1350360 |
| 14 | 284800 |
| 15 | 33800 |
| 16 | 2225 |
| 17 | 75 |
| 18 | 1 |
| 19 | 1728000 |
| 20 | 371520000 |
| 21 | 7629120000 |
| 22 | 42762240000 |
| 23 | 97388280000 |
| 24 | 110386900800 |
| 25 | 70137648000 |
| 26 | 26920728000 |
| 27 | 6548346000 |
| 28 | 1039382000 |
[1,120,600,600,200,25,1,14400,504000,2664000, 4608000,3501000,1350360,284800,33800,2225,75,1, 1728000,371520000,7629120000,42762240000, 97388280000,110386900800,70137648000,26920728000, 6548346000,1039382000] |