The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 5038 |
| 8 | 40066 |
| 9 | 353556 |
| 10 | 3399246 |
| 11 | 35142546 |
| 12 | 387129588 |
| 13 | 4515261680 |
| 14 | 55502974820 |
| 15 | 716557285110 |
| 16 | 9689420220510 |
| 17 | 136922907564972 |
| 18 | 2018121531850482 |
| 19 | 30972340185946810 |
| 20 | 494190208052390752 |
| 21 | 8186609585709287112 |
| 22 | 140620153367124829272 |
[1,1,2,6,24,120,720,5038,40066,353556,3399246, 35142546,387129588,4515261680,55502974820, 716557285110,9689420220510,136922907564972, 2018121531850482,30972340185946810, 494190208052390752,8186609585709287112, 140620153367124829272] |