The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 46 |
| 6 | 156 |
| 7 | 550 |
| 8 | 2012 |
| 9 | 7606 |
| 10 | 29449 |
| 11 | 116379 |
| 12 | 468297 |
| 13 | 1911897 |
| 14 | 7907479 |
| 15 | 33074959 |
| 16 | 139692623 |
| 17 | 595163091 |
| 18 | 2555275568 |
| 19 | 11046348101 |
| 20 | 48049939121 |
| 21 | 210177221656 |
| 22 | 924005069621 |
| 23 | 4080977703387 |
| 24 | 18099984139140 |
| 25 | 80587248455206 |
| 26 | 360075457598216 |
| 27 | 1614132248554453 |
| 28 | 7257668963955514 |
[1,1,2,5,15,46,156,550,2012,7606,29449,116379, 468297,1911897,7907479,33074959,139692623, 595163091,2555275568,11046348101,48049939121, 210177221656,924005069621,4080977703387, 18099984139140,80587248455206,360075457598216, 1614132248554453,7257668963955514] |