The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 24 |
| 4 | 144 |
| 5 | 1440 |
| 6 | 14400 |
| 7 | 201600 |
| 8 | 2822400 |
| 9 | 50803200 |
| 10 | 914457600 |
| 11 | 20118067200 |
| 12 | 442597478400 |
| 13 | 11507534438400 |
| 14 | 299195895398400 |
| 15 | 8975876861952000 |
| 16 | 269276305858560000 |
| 17 | 9155394399191040000 |
| 18 | 311283409572495360000 |
[1,2,4,24,144,1440,14400,201600,2822400,50803200, 914457600,20118067200,442597478400,11507534438400, 299195895398400,8975876861952000, 269276305858560000,9155394399191040000, 311283409572495360000] |