The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 5 |
| 3 | 15 |
| 4 | 61 |
| 5 | 237 |
| 6 | 975 |
| 7 | 4065 |
| 8 | 17241 |
| 9 | 73767 |
| 10 | 321065 |
| 11 | 1400101 |
| 12 | 6189569 |
| 13 | 27425379 |
| 14 | 122501931 |
| 15 | 548994421 |
| 16 | 2473297033 |
| 17 | 11172777749 |
| 18 | 50700588795 |
| 19 | 230493478249 |
| 20 | 1052010563401 |
| 21 | 4808670421383 |
| 22 | 22049797255923 |
| 23 | 101248208209155 |
| 24 | 466096354932527 |
| 25 | 2148323185236391 |
| 26 | 9923637821045399 |
| 27 | 45887368095632053 |
[1,1,5,15,61,237,975,4065,17241,73767,321065, 1400101,6189569,27425379,122501931,548994421, 2473297033,11172777749,50700588795,230493478249, 1052010563401,4808670421383,22049797255923, 101248208209155,466096354932527,2148323185236391, 9923637821045399,45887368095632053] |