The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 11 |
| 3 | 20 |
| 4 | 45 |
| 5 | 104 |
| 6 | 290 |
| 7 | 796 |
| 8 | 2366 |
| 9 | 7076 |
| 10 | 21684 |
| 11 | 66996 |
| 12 | 209594 |
| 13 | 659560 |
| 14 | 2090590 |
| 15 | 6659120 |
| 16 | 21312716 |
| 17 | 68476512 |
| 18 | 220798322 |
| 19 | 714144612 |
| 20 | 2316303916 |
| 21 | 7531662344 |
| 22 | 24545750474 |
| 23 | 80160395804 |
| 24 | 262280793024 |
| 25 | 859662037240 |
| 26 | 2822180991508 |
| 27 | 9278652591844 |
| 28 | 30547892144882 |
[6,11,20,45,104,290,796,2366,7076,21684,66996, 209594,659560,2090590,6659120,21312716,68476512, 220798322,714144612,2316303916,7531662344, 24545750474,80160395804,262280793024,859662037240, 2822180991508,9278652591844,30547892144882] |