The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 51 |
| 4 | 798 |
| 5 | 16914 |
| 6 | 453294 |
| 7 | 14704542 |
| 8 | 560274336 |
| 9 | 24529661568 |
| 10 | 1213557885720 |
| 11 | 66956662956600 |
| 12 | 4076440417367856 |
| 13 | 271472012197547472 |
| 14 | 19631093304600307152 |
| 15 | 1531919987372848152240 |
| 16 | 128314172533501646058240 |
| 17 | 11482569303348317402868480 |
| 18 | 1093343670892117401737893632 |
[1,1,5,51,798,16914,453294,14704542,560274336, 24529661568,1213557885720,66956662956600, 4076440417367856,271472012197547472, 19631093304600307152,1531919987372848152240, 128314172533501646058240, 11482569303348317402868480, 1093343670892117401737893632] |