The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 6 |
| 3 | 19 |
| 4 | 71 |
| 5 | 265 |
| 6 | 1058 |
| 7 | 4252 |
| 8 | 17711 |
| 9 | 74131 |
| 10 | 317076 |
| 11 | 1362358 |
| 12 | 5935160 |
| 13 | 25963188 |
| 14 | 114651556 |
| 15 | 508135189 |
| 16 | 2267288700 |
| 17 | 10148900369 |
| 18 | 45657273028 |
| 19 | 205973658612 |
| 20 | 932807045180 |
| 21 | 4234771468256 |
| 22 | 19284120926548 |
| 23 | 88002666104129 |
| 24 | 402601414827027 |
| 25 | 1845303695720157 |
| 26 | 8475413355494720 |
| 27 | 38991551867181771 |
[1,2,6,19,71,265,1058,4252,17711,74131,317076, 1362358,5935160,25963188,114651556,508135189, 2267288700,10148900369,45657273028,205973658612, 932807045180,4234771468256,19284120926548, 88002666104129,402601414827027,1845303695720157, 8475413355494720,38991551867181771] |