The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 78 |
| 4 | 816 |
| 5 | 10680 |
| 6 | 167760 |
| 7 | 3074400 |
| 8 | 64391040 |
| 9 | 1517201280 |
| 10 | 39720844800 |
| 11 | 1143895737600 |
| 12 | 35937095040000 |
| 13 | 1223098971494400 |
| 14 | 44829605505484800 |
| 15 | 1760481463732992000 |
| 16 | 73744004937867264000 |
| 17 | 3282093293695856640000 |
[1,2,10,78,816,10680,167760,3074400,64391040, 1517201280,39720844800,1143895737600, 35937095040000,1223098971494400,44829605505484800, 1760481463732992000,73744004937867264000, 3282093293695856640000] |