The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 37 |
| 5 | 257 |
| 6 | 1665 |
| 7 | 10695 |
| 8 | 68637 |
| 9 | 440509 |
| 10 | 2827377 |
| 11 | 18148003 |
| 12 | 116487861 |
| 13 | 747713321 |
| 14 | 4799439985 |
| 15 | 30806785967 |
| 16 | 197743565181 |
| 17 | 1269282762917 |
| 18 | 8147313444929 |
| 19 | 52296241209451 |
| 20 | 335680820572405 |
| 21 | 2154679016567857 |
[1,1,5,37,257,1665,10695,68637,440509,2827377, 18148003,116487861,747713321,4799439985, 30806785967,197743565181,1269282762917, 8147313444929,52296241209451,335680820572405, 2154679016567857] |