The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 5 |
| 3 | 15 |
| 4 | 60 |
| 5 | 245 |
| 6 | 826 |
| 7 | 2685 |
| 8 | 9285 |
| 9 | 33170 |
| 10 | 120170 |
| 11 | 440326 |
| 12 | 1615095 |
| 13 | 5883375 |
| 14 | 21190660 |
| 15 | 75236135 |
| 16 | 263524256 |
| 17 | 914398280 |
| 18 | 3157044220 |
| 19 | 10882619895 |
| 20 | 37556051395 |
| 21 | 130016429216 |
| 22 | 451988934200 |
| 23 | 1578008726440 |
| 24 | 5530356335910 |
| 25 | 19444175637910 |
| 26 | 68542014844306 |
| 27 | 242123225194065 |
| 28 | 856755084242890 |
[1,5,15,60,245,826,2685,9285,33170,120170,440326, 1615095,5883375,21190660,75236135,263524256, 914398280,3157044220,10882619895,37556051395, 130016429216,451988934200,1578008726440, 5530356335910,19444175637910,68542014844306, 242123225194065,856755084242890] |