The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 8 |
| 5 | 19 |
| 6 | 52 |
| 7 | 140 |
| 8 | 479 |
| 9 | 1464 |
| 10 | 5596 |
| 11 | 19334 |
| 12 | 78841 |
| 13 | 305406 |
| 14 | 1295435 |
| 15 | 5527265 |
| 16 | 24403208 |
| 17 | 112338932 |
| 18 | 517908324 |
| 19 | 2531226446 |
| 20 | 12216601247 |
| 21 | 62626424572 |
| 22 | 316570510625 |
| 23 | 1688123202118 |
| 24 | 8924364770995 |
| 25 | 49245542104325 |
| 26 | 271541015196694 |
| 27 | 1545740618597036 |
[1,1,3,8,19,52,140,479,1464,5596,19334,78841, 305406,1295435,5527265,24403208,112338932, 517908324,2531226446,12216601247,62626424572, 316570510625,1688123202118,8924364770995, 49245542104325,271541015196694,1545740618597036] |