The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 17 |
| 4 | 152 |
| 5 | 1944 |
| 6 | 33404 |
| 7 | 738212 |
| 8 | 20316288 |
| 9 | 679237248 |
| 10 | 27050017152 |
| 11 | 1262790237312 |
| 12 | 68193683598336 |
| 13 | 4212508572109824 |
| 14 | 294822473048043264 |
| 15 | 23184842446161993984 |
| 16 | 2033884583922970558464 |
| 17 | 197767395237549512097792 |
| 18 | 21194678534706844531458048 |
[1,1,3,17,152,1944,33404,738212,20316288, 679237248,27050017152,1262790237312, 68193683598336,4212508572109824, 294822473048043264,23184842446161993984, 2033884583922970558464,197767395237549512097792, 21194678534706844531458048] |