The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 6 |
| 4 | 23 |
| 5 | 73 |
| 6 | 211 |
| 7 | 581 |
| 8 | 1560 |
| 9 | 4135 |
| 10 | 10890 |
| 11 | 28590 |
| 12 | 74946 |
| 13 | 196326 |
| 14 | 514123 |
| 15 | 1346148 |
| 16 | 3524441 |
| 17 | 9227311 |
| 18 | 24157645 |
| 19 | 63245795 |
| 20 | 165579930 |
| 21 | 433494205 |
| 22 | 1134902916 |
| 23 | 2971214796 |
| 24 | 7778741748 |
| 25 | 20365010748 |
| 26 | 53316290821 |
| 27 | 139583862066 |
[1,6,23,73,211,581,1560,4135,10890,28590,74946, 196326,514123,1346148,3524441,9227311,24157645, 63245795,165579930,433494205,1134902916, 2971214796,7778741748,20365010748,53316290821, 139583862066] |