The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 17 |
| 4 | 72 |
| 5 | 357 |
| 6 | 2022 |
| 7 | 12900 |
| 8 | 91448 |
| 9 | 711180 |
| 10 | 6004981 |
| 11 | 54619489 |
| 12 | 531854438 |
| 13 | 5515551251 |
| 14 | 60642234815 |
| 15 | 704106298738 |
| 16 | 8603658260904 |
| 17 | 110306422692488 |
| 18 | 1479905106340895 |
| 19 | 20727595895871297 |
| 20 | 302423908621734606 |
[1,2,5,17,72,357,2022,12900,91448,711180,6004981, 54619489,531854438,5515551251,60642234815, 704106298738,8603658260904,110306422692488, 1479905106340895,20727595895871297, 302423908621734606] |