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 | 21 |
| 5 | 59 |
| 6 | 224 |
| 7 | 778 |
| 8 | 3074 |
| 9 | 11996 |
| 10 | 49040 |
| 11 | 203505 |
| 12 | 860069 |
| 13 | 3696639 |
| 14 | 16073620 |
| 15 | 70742766 |
| 16 | 314411761 |
| 17 | 1409236688 |
| 18 | 6367263724 |
| 19 | 28958423806 |
| 20 | 132525828708 |
| 21 | 609812684776 |
| 22 | 2819761081437 |
| 23 | 13097700679165 |
| 24 | 61082151474216 |
| 25 | 285923856913975 |
| 26 | 1342918625701453 |
| 27 | 6326900756629652 |
| 28 | 29893296939002381 |
[1,1,3,6,21,59,224,778,3074,11996,49040,203505, 860069,3696639,16073620,70742766,314411761, 1409236688,6367263724,28958423806,132525828708, 609812684776,2819761081437,13097700679165, 61082151474216,285923856913975,1342918625701453, 6326900756629652,29893296939002381] |