The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 11 |
| 4 | 45 |
| 5 | 170 |
| 6 | 538 |
| 7 | 1674 |
| 8 | 5410 |
| 9 | 18001 |
| 10 | 60486 |
| 11 | 202486 |
| 12 | 674159 |
| 13 | 2238695 |
| 14 | 7433743 |
| 15 | 24704751 |
| 16 | 82150290 |
| 17 | 273210105 |
| 18 | 908536081 |
| 19 | 3020918528 |
| 20 | 10044214676 |
| 21 | 33396046046 |
| 22 | 111040661940 |
| 23 | 369210326847 |
| 24 | 1227626858414 |
| 25 | 4081857794878 |
[1,2,11,45,170,538,1674,5410,18001,60486,202486, 674159,2238695,7433743,24704751,82150290, 273210105,908536081,3020918528,10044214676, 33396046046,111040661940,369210326847, 1227626858414,4081857794878] |