The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 38 |
| 5 | 404 |
| 6 | 5514 |
| 7 | 91916 |
| 8 | 1810080 |
| 9 | 41119704 |
| 10 | 1058505600 |
| 11 | 30450551592 |
| 12 | 968121778128 |
| 13 | 33709242522864 |
| 14 | 1275738359407680 |
| 15 | 52141501470591360 |
| 16 | 2288907292892799744 |
| 17 | 107405692000948859904 |
| 18 | 5365016291068305805440 |
| 19 | 284225212617080543066880 |
[0,1,1,5,38,404,5514,91916,1810080,41119704, 1058505600,30450551592,968121778128, 33709242522864,1275738359407680,52141501470591360, 2288907292892799744,107405692000948859904, 5365016291068305805440,284225212617080543066880] |