The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 19 |
| 5 | 53 |
| 6 | 174 |
| 7 | 578 |
| 8 | 1995 |
| 9 | 7216 |
| 10 | 26344 |
| 11 | 99728 |
| 12 | 381800 |
| 13 | 1492177 |
| 14 | 5915918 |
| 15 | 23744011 |
| 16 | 96564899 |
| 17 | 396388960 |
| 18 | 1644245678 |
| 19 | 6876168960 |
| 20 | 28989823670 |
| 21 | 123106176598 |
| 22 | 526195843753 |
| 23 | 2263275385587 |
| 24 | 9788573310743 |
| 25 | 42562654829075 |
| 26 | 185963233778672 |
| 27 | 816227682031374 |
| 28 | 3597876689102063 |
[1,1,3,6,19,53,174,578,1995,7216,26344,99728, 381800,1492177,5915918,23744011,96564899, 396388960,1644245678,6876168960,28989823670, 123106176598,526195843753,2263275385587, 9788573310743,42562654829075,185963233778672, 816227682031374,3597876689102063] |