| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 20 |
| 2 | 180 |
| 3 | 960 |
| 4 | 3380 |
| 5 | 8424 |
| 6 | 16320 |
| 7 | 28800 |
| 8 | 52020 |
| 9 | 88660 |
| 10 | 129064 |
| 11 | 175680 |
| 12 | 262080 |
| 13 | 386920 |
| 14 | 489600 |
| 15 | 600960 |
| 16 | 840500 |
| 17 | 1137960 |
| 18 | 1330420 |
| 19 | 1563840 |
| 20 | 2050344 |
| 21 | 2611200 |
| 22 | 2986560 |
| 23 | 3358080 |
| 24 | 4194240 |
| 25 | 5318268 |
| 26 | 5878440 |
| 27 | 6299520 |
| 28 | 7862400 |
| 29 | 9619560 |
[1,20,180,960,3380,8424,16320,28800,52020,88660, 129064,175680,262080,386920,489600,600960,840500, 1137960,1330420,1563840,2050344,2611200,2986560, 3358080,4194240,5318268,5878440,6299520,7862400, 9619560] |