The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 20 |
| 5 | 5 |
| 6 | 198 |
| 7 | 7 |
| 8 | 1544 |
| 9 | 19692 |
| 10 | 10250 |
| 11 | 11 |
| 12 | 2187216 |
| 13 | 13 |
| 14 | 344078 |
| 15 | 143489085 |
| 16 | 4296802320 |
| 17 | 17 |
| 18 | 7757846982 |
| 19 | 19 |
| 20 | 5497605324820 |
| 21 | 366112362126 |
| 22 | 230686742 |
| 23 | 23 |
| 24 | 4237941811999056 |
| 25 | 298023223876953150 |
| 26 | 5234491418 |
| 27 | 640550188738935 |
| 28 | 2522015815755104284 |
[1,2,3,20,5,198,7,1544,19692,10250,11,2187216,13, 344078,143489085,4296802320,17,7757846982,19, 5497605324820,366112362126,230686742,23, 4237941811999056,298023223876953150,5234491418, 640550188738935,2522015815755104284] |