The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 56 |
| 3 | 192 |
| 4 | 1672 |
| 5 | 25080 |
| 6 | 146688 |
| 7 | 1346944 |
| 8 | 13834555 |
| 9 | 104830640 |
| 10 | 937391448 |
| 11 | 8580314512 |
| 12 | 71419802456 |
| 13 | 629686664072 |
| 14 | 5565143259715 |
| 15 | 47786322624048 |
| 16 | 418580670492536 |
| 17 | 3662684910895709 |
| 18 | 31774718564557848 |
| 19 | 277532293674535584 |
[0,56,192,1672,25080,146688,1346944,13834555, 104830640,937391448,8580314512,71419802456, 629686664072,5565143259715,47786322624048, 418580670492536,3662684910895709, 31774718564557848,277532293674535584] |