The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 10 |
| 5 | 27 |
| 6 | 118 |
| 7 | 389 |
| 8 | 1688 |
| 9 | 6357 |
| 10 | 28302 |
| 11 | 117301 |
| 12 | 541832 |
| 13 | 2418649 |
| 14 | 11629794 |
| 15 | 55165477 |
| 16 | 276131564 |
| 17 | 1379441105 |
| 18 | 7178203950 |
| 19 | 37525908261 |
| 20 | 202624599112 |
| 21 | 1103246397377 |
| 22 | 6168861375178 |
| 23 | 34853267706981 |
| 24 | 201412524836788 |
| 25 | 1177304020632257 |
| 26 | 7018267240899110 |
[0,0,1,2,10,27,118,389,1688,6357,28302,117301, 541832,2418649,11629794,55165477,276131564, 1379441105,7178203950,37525908261,202624599112, 1103246397377,6168861375178,34853267706981, 201412524836788,1177304020632257,7018267240899110] |