| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 24 |
| 4 | 120 |
| 5 | 624 |
| 6 | 3096 |
| 7 | 15624 |
| 8 | 78000 |
| 9 | 390600 |
| 10 | 1952496 |
| 11 | 9765624 |
| 12 | 48824880 |
| 13 | 244140624 |
| 14 | 1220687496 |
| 15 | 6103514976 |
| 16 | 30517500000 |
| 17 | 152587890624 |
| 18 | 762939059400 |
| 19 | 3814697265624 |
| 20 | 19073484374880 |
| 21 | 95367431624976 |
| 22 | 476837148437496 |
| 23 | 2384185791015624 |
| 24 | 11920928906172000 |
[1,4,24,120,624,3096,15624,78000,390600,1952496, 9765624,48824880,244140624,1220687496,6103514976, 30517500000,152587890624,762939059400, 3814697265624,19073484374880,95367431624976, 476837148437496,2384185791015624, 11920928906172000] |