The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 24 |
| 5 | 64 |
| 6 | 234 |
| 7 | 753 |
| 8 | 2814 |
| 9 | 9631 |
| 10 | 36590 |
| 11 | 133154 |
| 12 | 508094 |
| 13 | 1892979 |
| 14 | 7412897 |
| 15 | 28214787 |
| 16 | 110971333 |
| 17 | 430260008 |
| 18 | 1715691772 |
| 19 | 6714923487 |
| 20 | 26987686029 |
| 21 | 107015958439 |
| 22 | 432609065273 |
| 23 | 1727698411048 |
| 24 | 7039239456777 |
| 25 | 28333176820004 |
| 26 | 115868253070447 |
| 27 | 469484246174260 |
| 28 | 1930438223562659 |
[1,1,3,6,24,64,234,753,2814,9631,36590,133154, 508094,1892979,7412897,28214787,110971333, 430260008,1715691772,6714923487,26987686029, 107015958439,432609065273,1727698411048, 7039239456777,28333176820004,115868253070447, 469484246174260,1930438223562659] |