The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 22 |
| 5 | 66 |
| 6 | 227 |
| 7 | 758 |
| 8 | 2741 |
| 9 | 9861 |
| 10 | 36917 |
| 11 | 138933 |
| 12 | 535499 |
| 13 | 2077759 |
| 14 | 8190950 |
| 15 | 32516955 |
| 16 | 130479483 |
| 17 | 527198671 |
| 18 | 2147012696 |
| 19 | 8795672388 |
| 20 | 36264715700 |
| 21 | 150285288597 |
| 22 | 626008650470 |
| 23 | 2619473550761 |
| 24 | 11007963517106 |
| 25 | 46439591494941 |
| 26 | 196648771804289 |
| 27 | 835525524895916 |
| 28 | 3561426453988150 |
[1,1,3,7,22,66,227,758,2741,9861,36917,138933, 535499,2077759,8190950,32516955,130479483, 527198671,2147012696,8795672388,36264715700, 150285288597,626008650470,2619473550761, 11007963517106,46439591494941,196648771804289, 835525524895916,3561426453988150] |