The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 30 |
| 6 | 87 |
| 7 | 273 |
| 8 | 1060 |
| 9 | 4629 |
| 10 | 22118 |
| 11 | 114675 |
| 12 | 637508 |
| 13 | 3764980 |
| 14 | 23493473 |
| 15 | 154648476 |
| 16 | 1074598386 |
| 17 | 7847796726 |
| 18 | 59999039043 |
| 19 | 478914675838 |
| 20 | 3978488873259 |
| 21 | 34374954527318 |
| 22 | 308440229973719 |
| 23 | 2865860328108722 |
| 24 | 27538413740887632 |
[1,2,4,11,30,87,273,1060,4629,22118,114675,637508, 3764980,23493473,154648476,1074598386,7847796726, 59999039043,478914675838,3978488873259, 34374954527318,308440229973719,2865860328108722, 27538413740887632] |