The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 42 |
| 4 | 287 |
| 5 | 2114 |
| 6 | 16338 |
| 7 | 130802 |
| 8 | 1075355 |
| 9 | 9025656 |
| 10 | 77021482 |
| 11 | 666267502 |
| 12 | 5829209046 |
| 13 | 51492030953 |
| 14 | 458612500526 |
| 15 | 4113879873624 |
| 16 | 37133888342707 |
| 17 | 337041718357465 |
| 18 | 3074153880004188 |
| 19 | 28162578841220534 |
| 20 | 259020296989987934 |
| 21 | 2390818256963083305 |
[1,1,7,42,287,2114,16338,130802,1075355,9025656, 77021482,666267502,5829209046,51492030953, 458612500526,4113879873624,37133888342707, 337041718357465,3074153880004188, 28162578841220534,259020296989987934, 2390818256963083305] |