The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 30 |
| 4 | 264 |
| 5 | 3000 |
| 6 | 40320 |
| 7 | 635040 |
| 8 | 11410560 |
| 9 | 230791680 |
| 10 | 5185555200 |
| 11 | 128172844800 |
| 12 | 3455996544000 |
| 13 | 100952461209600 |
| 14 | 3175730791833600 |
| 15 | 107037070043904000 |
| 16 | 3848161361780736000 |
| 17 | 146994587721805824000 |
[1,1,4,30,264,3000,40320,635040,11410560, 230791680,5185555200,128172844800,3455996544000, 100952461209600,3175730791833600, 107037070043904000,3848161361780736000, 146994587721805824000] |