The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 17 |
| 3 | 114 |
| 4 | 564 |
| 5 | 2507 |
| 6 | 10961 |
| 7 | 49260 |
| 8 | 231928 |
| 9 | 1150781 |
| 10 | 6017297 |
| 11 | 33085294 |
| 12 | 190777804 |
| 13 | 1150650935 |
| 14 | 7241707281 |
| 15 | 47454741400 |
| 16 | 323154690928 |
| 17 | 2282779984281 |
| 18 | 16700904481425 |
| 19 | 126356632381834 |
| 20 | 987303454919204 |
| 21 | 7957133905597635 |
| 22 | 66071772829234641 |
[0,1,17,114,564,2507,10961,49260,231928,1150781, 6017297,33085294,190777804,1150650935,7241707281, 47454741400,323154690928,2282779984281, 16700904481425,126356632381834,987303454919204, 7957133905597635,66071772829234641] |