The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 13 |
| 5 | 65 |
| 6 | 351 |
| 7 | 1999 |
| 8 | 11872 |
| 9 | 73023 |
| 10 | 462889 |
| 11 | 3012162 |
| 12 | 20056509 |
| 13 | 136274564 |
| 14 | 942624033 |
| 15 | 6624531216 |
| 16 | 47219125251 |
| 17 | 340867497305 |
| 18 | 2488891555146 |
| 19 | 18361241675953 |
| 20 | 136728796412286 |
| 21 | 1026878910257061 |
| 22 | 7772561249596928 |
| 23 | 59253932922240432 |
| 24 | 454708539839137050 |
[1,1,3,13,65,351,1999,11872,73023,462889,3012162, 20056509,136274564,942624033,6624531216, 47219125251,340867497305,2488891555146, 18361241675953,136728796412286,1026878910257061, 7772561249596928,59253932922240432, 454708539839137050] |