The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 120 |
| 6 | 720 |
| 7 | 2640 |
| 8 | 13596 |
| 9 | 87768 |
| 10 | 680274 |
| 11 | 6090756 |
| 12 | 61678252 |
| 13 | 482005340 |
| 14 | 4454053680 |
| 15 | 46705656280 |
| 16 | 549750105234 |
[1,2,6,24,120,720,2640,13596,87768,680274,6090756, 61678252,482005340,4454053680,46705656280, 549750105234] |