The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 22 |
| 4 | 14 |
| 5 | 70 |
| 6 | 154 |
| 7 | 486 |
| 8 | 1602 |
| 9 | 5777 |
| 10 | 10188 |
| 11 | 28506 |
| 12 | 101227 |
| 13 | 267042 |
| 14 | 698241 |
| 15 | 2005275 |
| 16 | 5355840 |
| 17 | 15507088 |
| 18 | 43713710 |
| 19 | 117062325 |
| 20 | 328169426 |
| 21 | 927529600 |
| 22 | 2543571216 |
| 23 | 7113125250 |
| 24 | 19776079964 |
| 25 | 54664483400 |
| 26 | 152873904217 |
| 27 | 425365839757 |
[1,1,22,14,70,154,486,1602,5777,10188,28506, 101227,267042,698241,2005275,5355840,15507088, 43713710,117062325,328169426,927529600,2543571216, 7113125250,19776079964,54664483400,152873904217, 425365839757] |