The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 1640 |
| 3 | 89610 |
| 4 | 5390325 |
| 5 | 314688054 |
| 6 | 18550312526 |
| 7 | 1089970014327 |
| 8 | 64114204398028 |
| 9 | 3769915844080995 |
| 10 | 221699388876599524 |
| 11 | 13037021233036033635 |
| 12 | 766652822812020772883 |
| 13 | 45083423150083817466414 |
| 14 | 2651159090798112000786121 |
[21,1640,89610,5390325,314688054,18550312526, 1089970014327,64114204398028,3769915844080995, 221699388876599524,13037021233036033635, 766652822812020772883,45083423150083817466414, 2651159090798112000786121] |