The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 11 |
| 6 | 35 |
| 7 | 122 |
| 8 | 440 |
| 9 | 1609 |
| 10 | 5913 |
| 11 | 21770 |
| 12 | 80204 |
| 13 | 295555 |
| 14 | 1089227 |
| 15 | 4014322 |
| 16 | 14794864 |
| 17 | 54526993 |
| 18 | 200961457 |
| 19 | 740652050 |
| 20 | 2729705364 |
| 21 | 10060448635 |
| 22 | 37078224883 |
| 23 | 136653426026 |
| 24 | 503642204200 |
| 25 | 1856195468633 |
| 26 | 6841089945545 |
[0,1,1,2,4,11,35,122,440,1609,5913,21770,80204, 295555,1089227,4014322,14794864,54526993, 200961457,740652050,2729705364,10060448635, 37078224883,136653426026,503642204200, 1856195468633,6841089945545] |