The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 12 |
| 3 | 60 |
| 4 | 420 |
| 5 | 3456 |
| 6 | 60060 |
| 7 | 155520 |
| 8 | 1512000 |
| 9 | 13063680 |
| 10 | 169344000 |
| 11 | 1524096000 |
| 12 | 16765056000 |
| 13 | 217945728000 |
| 14 | 3705077376000 |
| 15 | 52306974720000 |
| 16 | 889218570240000 |
| 17 | 16895152834560000 |
| 18 | 328655183560704000 |
| 19 | 6244448487653376000 |
| 20 | 143622315216027648000 |
| 21 | 2922401892221779968000 |
| 22 | 67215243521100939264000 |
[2,12,60,420,3456,60060,155520,1512000,13063680, 169344000,1524096000,16765056000,217945728000, 3705077376000,52306974720000,889218570240000, 16895152834560000,328655183560704000, 6244448487653376000,143622315216027648000, 2922401892221779968000,67215243521100939264000] |