The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 704 |
| 3 | 2176 |
| 4 | 30976 |
| 5 | 166272 |
| 6 | 1567936 |
| 7 | 10419200 |
| 8 | 85438016 |
| 9 | 615338112 |
| 10 | 4793908736 |
| 11 | 35590710400 |
| 12 | 272110337728 |
| 13 | 2043420143616 |
| 14 | 15514205504320 |
| 15 | 117001754129792 |
| 16 | 885993008059136 |
| 17 | 6692427408972672 |
| 18 | 50629009974094016 |
| 19 | 382657950434206720 |
[0,704,2176,30976,166272,1567936,10419200, 85438016,615338112,4793908736,35590710400, 272110337728,2043420143616,15514205504320, 117001754129792,885993008059136,6692427408972672, 50629009974094016,382657950434206720] |