The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 10 |
| 3 | 74 |
| 4 | 515 |
| 5 | 3540 |
| 6 | 24276 |
| 7 | 166405 |
| 8 | 1140574 |
| 9 | 7817630 |
| 10 | 53582855 |
| 11 | 367262376 |
| 12 | 2517253800 |
| 13 | 17253514249 |
| 14 | 118257345970 |
| 15 | 810547907570 |
| 16 | 5555578007051 |
| 17 | 38078498141820 |
| 18 | 260993908985724 |
| 19 | 1788878864758285 |
| 20 | 12261158144322310 |
[0,1,10,74,515,3540,24276,166405,1140574,7817630, 53582855,367262376,2517253800,17253514249, 118257345970,810547907570,5555578007051, 38078498141820,260993908985724,1788878864758285, 12261158144322310] |