The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 3 | 1 |
| 4 | 42 |
| 5 | 420 |
| 6 | 3786 |
| 7 | 33648 |
| 8 | 297940 |
| 9 | 2633872 |
| 10 | 23265744 |
| 11 | 205446960 |
| 12 | 1814136746 |
| 13 | 16021697220 |
| 14 | 141535810130 |
| 15 | 1250763720312 |
| 16 | 11057433981126 |
| 17 | 97794407702052 |
| 18 | 865284559977150 |
| 19 | 7659315417653664 |
| 20 | 67827407480624862 |
| 21 | 600898634852988364 |
| 22 | 5325658497658529790 |
[1,42,420,3786,33648,297940,2633872,23265744, 205446960,1814136746,16021697220,141535810130, 1250763720312,11057433981126,97794407702052, 865284559977150,7659315417653664, 67827407480624862,600898634852988364, 5325658497658529790] |