The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 31 |
| 5 | 105 |
| 6 | 380 |
| 7 | 1424 |
| 8 | 5451 |
| 9 | 21236 |
| 10 | 84023 |
| 11 | 336837 |
| 12 | 1366529 |
| 13 | 5597986 |
| 14 | 23129943 |
| 15 | 96272760 |
| 16 | 403427906 |
| 17 | 1701008029 |
| 18 | 7211480972 |
| 19 | 30724854989 |
| 20 | 131497271065 |
| 21 | 565125754561 |
| 22 | 2438042909441 |
| 23 | 10555465139832 |
| 24 | 45849803838254 |
| 25 | 199765279212025 |
| 26 | 872844372120064 |
| 27 | 3823935236078622 |
| 28 | 16794571990271903 |
[1,1,3,9,31,105,380,1424,5451,21236,84023,336837, 1366529,5597986,23129943,96272760,403427906, 1701008029,7211480972,30724854989,131497271065, 565125754561,2438042909441,10555465139832, 45849803838254,199765279212025,872844372120064, 3823935236078622,16794571990271903] |