The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 4 | 6 |
| 5 | 120 |
| 6 | 2160 |
| 7 | 41160 |
| 8 | 861420 |
| 9 | 19949328 |
| 10 | 510320160 |
| 11 | 14348862000 |
| 12 | 440879024520 |
| 13 | 14716697990280 |
| 14 | 530761366078944 |
| 15 | 20577610843203960 |
| 16 | 853717568817968400 |
| 17 | 37746072677473752480 |
| 18 | 1771994498414094109440 |
| 19 | 88032162789004128733152 |
| 20 | 4614300279345812506938720 |
[6,120,2160,41160,861420,19949328,510320160, 14348862000,440879024520,14716697990280, 530761366078944,20577610843203960, 853717568817968400,37746072677473752480, 1771994498414094109440,88032162789004128733152, 4614300279345812506938720] |