The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 55 |
| 5 | 273 |
| 6 | 1428 |
| 7 | 7752 |
| 8 | 43263 |
| 9 | 246675 |
| 10 | 1430715 |
| 11 | 8414640 |
| 12 | 50067108 |
| 13 | 300830572 |
| 14 | 1822766520 |
| 15 | 11124755664 |
| 16 | 68328754959 |
| 17 | 422030545335 |
| 18 | 2619631042665 |
| 19 | 16332922290300 |
| 20 | 102240109897695 |
| 21 | 642312451217745 |
| 22 | 4048514844039120 |
| 23 | 25594403741131680 |
| 24 | 162250238001816900 |
[1,1,3,12,55,273,1428,7752,43263,246675,1430715, 8414640,50067108,300830572,1822766520,11124755664, 68328754959,422030545335,2619631042665, 16332922290300,102240109897695,642312451217745, 4048514844039120,25594403741131680, 162250238001816900] |