The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 23 |
| 3 | 55 |
| 4 | 279 |
| 5 | 895 |
| 6 | 3696 |
| 7 | 13289 |
| 8 | 51734 |
| 9 | 192418 |
| 10 | 735241 |
| 11 | 2765966 |
| 12 | 10501378 |
| 13 | 39658770 |
| 14 | 150239389 |
| 15 | 568125614 |
| 16 | 2150618007 |
| 17 | 8136093736 |
| 18 | 30791019947 |
| 19 | 116504256865 |
| 20 | 440871748994 |
| 21 | 1668215077887 |
| 22 | 6312621082911 |
| 23 | 23886745061996 |
[1,23,55,279,895,3696,13289,51734,192418,735241, 2765966,10501378,39658770,150239389,568125614, 2150618007,8136093736,30791019947,116504256865, 440871748994,1668215077887,6312621082911, 23886745061996] |