The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 10 |
| 3 | 6 |
| 4 | 12 |
| 5 | 9888 |
| 6 | 90 |
| 7 | 672 |
| 8 | 37680 |
| 9 | 3422877696 |
| 10 | 159840 |
| 11 | 35640 |
| 12 | 2977920 |
| 13 | 61724520 |
| 14 | 9530611200 |
| 15 | 272065167360 |
| 16 | 613958400 |
[2,10,6,12,9888,90,672,37680,3422877696,159840, 35640,2977920,61724520,9530611200,272065167360, 613958400] |