The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 60 |
| 3 | 452 |
| 4 | 3404 |
| 5 | 25636 |
| 6 | 193068 |
| 7 | 1454020 |
| 8 | 10950412 |
| 9 | 82468964 |
| 10 | 621084396 |
| 11 | 4677466628 |
| 12 | 35226603980 |
| 13 | 265296094372 |
| 14 | 1997979076524 |
| 15 | 15047037913156 |
| 16 | 113321181698188 |
| 17 | 853436423539940 |
| 18 | 6427339691572332 |
| 19 | 48405123535166084 |
| 20 | 364545223512451916 |
| 21 | 2745437058727827748 |
[1,8,60,452,3404,25636,193068,1454020,10950412, 82468964,621084396,4677466628,35226603980, 265296094372,1997979076524,15047037913156, 113321181698188,853436423539940,6427339691572332, 48405123535166084,364545223512451916, 2745437058727827748] |