| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 72 |
| 3 | 720 |
| 4 | 7920 |
| 5 | 95040 |
| 6 | 1235520 |
| 7 | 17297280 |
| 8 | 259459200 |
| 9 | 4151347200 |
| 10 | 70572902400 |
| 11 | 1270312243200 |
| 12 | 24135932620800 |
| 13 | 482718652416000 |
| 14 | 10137091700736000 |
| 15 | 223016017416192000 |
| 16 | 5129368400572416000 |
| 17 | 123104841613737984000 |
| 18 | 3077621040343449600000 |
| 19 | 80018147048929689600000 |
[1,8,72,720,7920,95040,1235520,17297280,259459200, 4151347200,70572902400,1270312243200, 24135932620800,482718652416000,10137091700736000, 223016017416192000,5129368400572416000, 123104841613737984000,3077621040343449600000, 80018147048929689600000] |