The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 2 |
| 4 | 4 |
| 5 | 13 |
| 6 | 32 |
| 7 | 93 |
| 8 | 274 |
| 9 | 861 |
| 10 | 2830 |
| 11 | 9707 |
| 12 | 34662 |
| 13 | 128442 |
| 14 | 492747 |
| 15 | 1952714 |
| 16 | 7978537 |
| 17 | 33552502 |
| 18 | 145002884 |
| 19 | 643093018 |
| 20 | 2923285048 |
| 21 | 13604173759 |
| 22 | 64747674282 |
| 23 | 314856179539 |
| 24 | 1562985778041 |
| 25 | 7914087230121 |
| 26 | 40843626440195 |
| 27 | 214695804264578 |
| 28 | 1148729745111018 |
| 29 | 6252380887804219 |
[1,2,2,4,13,32,93,274,861,2830,9707,34662,128442, 492747,1952714,7978537,33552502,145002884, 643093018,2923285048,13604173759,64747674282, 314856179539,1562985778041,7914087230121, 40843626440195,214695804264578,1148729745111018, 6252380887804219] |