The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 1 |
| 6 | 3 |
| 7 | 9 |
| 8 | 19 |
| 9 | 43 |
| 10 | 151 |
| 11 | 665 |
| 12 | 3477 |
| 13 | 19383 |
| 14 | 122069 |
| 15 | 922803 |
| 16 | 8541115 |
| 17 | 92856889 |
| 18 | 1171563865 |
| 19 | 17291558591 |
| 20 | 299747161375 |
| 21 | 6126738372415 |
| 22 | 147219368035745 |
| 23 | 4156365837186519 |
[1,1,1,1,1,3,9,19,43,151,665,3477,19383,122069, 922803,8541115,92856889,1171563865,17291558591, 299747161375,6126738372415,147219368035745, 4156365837186519] |