The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 12 |
| 3 | 56 |
| 4 | 240 |
| 5 | 992 |
| 6 | 1344 |
| 7 | 16256 |
| 8 | 60480 |
| 9 | 65520 |
| 10 | 1047552 |
| 11 | 4357080 |
| 12 | 47139840 |
| 13 | 67100672 |
| 14 | 91065600 |
| 15 | 285981696 |
| 16 | 919636480 |
| 17 | 2758909440 |
| 18 | 2952609792 |
| 19 | 17179738112 |
| 20 | 28364878080 |
| 21 | 63996791040 |
| 22 | 87722956800 |
| 23 | 102002360320 |
| 24 | 132867440640 |
| 25 | 137438691328 |
[2,12,56,240,992,1344,16256,60480,65520,1047552, 4357080,47139840,67100672,91065600,285981696, 919636480,2758909440,2952609792,17179738112, 28364878080,63996791040,87722956800,102002360320, 132867440640,137438691328] |