| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 4 |
| 3 | 100 |
| 4 | 1584 |
| 5 | 23548 |
| 6 | 338100 |
| 7 | 4798248 |
| 8 | 67750848 |
| 9 | 954701400 |
| 10 | 13441659268 |
| 11 | 189185124940 |
| 12 | 2662308356400 |
| 13 | 37463104912660 |
| 14 | 527155118240244 |
| 15 | 7417689205890000 |
| 16 | 104375121328998144 |
| 17 | 1468671237346368048 |
| 18 | 20665783224031936900 |
| 19 | 290789699203441908148 |
[0,0,4,100,1584,23548,338100,4798248,67750848, 954701400,13441659268,189185124940,2662308356400, 37463104912660,527155118240244,7417689205890000, 104375121328998144,1468671237346368048, 20665783224031936900,290789699203441908148] |