The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 16 |
| 3 | 144 |
| 4 | 768 |
| 5 | 3200 |
| 6 | 11520 |
| 7 | 37632 |
| 8 | 114688 |
| 9 | 331776 |
| 10 | 921600 |
| 11 | 2478080 |
| 12 | 6488064 |
| 13 | 16613376 |
| 14 | 41746432 |
| 15 | 103219200 |
| 16 | 251658240 |
| 17 | 606076928 |
| 18 | 1443889152 |
| 19 | 3406823424 |
| 20 | 7969177600 |
| 21 | 18496880640 |
| 22 | 42630905856 |
| 23 | 97626619904 |
| 24 | 222264557568 |
[0,16,144,768,3200,11520,37632,114688,331776, 921600,2478080,6488064,16613376,41746432, 103219200,251658240,606076928,1443889152, 3406823424,7969177600,18496880640,42630905856, 97626619904,222264557568] |