The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 19 |
| 5 | 63 |
| 6 | 219 |
| 7 | 787 |
| 8 | 2897 |
| 9 | 10869 |
| 10 | 41414 |
| 11 | 159822 |
| 12 | 623391 |
| 13 | 2453727 |
| 14 | 9733866 |
| 15 | 38877318 |
| 16 | 156206233 |
| 17 | 630947421 |
| 18 | 2560537092 |
| 19 | 10435207116 |
| 20 | 42689715279 |
| 21 | 175243923783 |
| 22 | 721649457417 |
| 23 | 2980276087005 |
| 24 | 12340456995177 |
| 25 | 51222441676513 |
[1,1,2,6,19,63,219,787,2897,10869,41414,159822, 623391,2453727,9733866,38877318,156206233, 630947421,2560537092,10435207116,42689715279, 175243923783,721649457417,2980276087005, 12340456995177,51222441676513] |