The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 25 |
| 3 | 249 |
| 4 | 2010 |
| 5 | 15892 |
| 6 | 124138 |
| 7 | 967227 |
| 8 | 7526784 |
| 9 | 58523196 |
| 10 | 454899087 |
| 11 | 3535406433 |
| 12 | 27474739134 |
| 13 | 213507824531 |
| 14 | 1659158104204 |
| 15 | 12893145686369 |
| 16 | 100191000314780 |
| 17 | 778570499896775 |
| 18 | 6050160661869467 |
| 19 | 47014925142895007 |
| 20 | 365346149954563938 |
[4,25,249,2010,15892,124138,967227,7526784, 58523196,454899087,3535406433,27474739134, 213507824531,1659158104204,12893145686369, 100191000314780,778570499896775,6050160661869467, 47014925142895007,365346149954563938] |