The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 6 |
| 6 | 13 |
| 7 | 37 |
| 8 | 134 |
| 9 | 659 |
| 10 | 4416 |
| 11 | 41343 |
| 12 | 546577 |
| 13 | 10345970 |
| 14 | 283128770 |
| 15 | 11306821624 |
| 16 | 664047579721 |
| 17 | 57753201767477 |
| 18 | 7483309752358051 |
[1,1,2,3,6,13,37,134,659,4416,41343,546577, 10345970,283128770,11306821624,664047579721, 57753201767477,7483309752358051] |