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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 28 |
| 5 | 570 |
| 6 | 10700 |
| 7 | 200235 |
| 8 | 3857672 |
| 9 | 77620788 |
| 10 | 1641549000 |
| 11 | 36576771165 |
| 12 | 859032716740 |
| 13 | 21251178078702 |
| 14 | 553095031003060 |
| 15 | 15122143306215855 |
| 16 | 433634860865610320 |
| 17 | 13020228528050054760 |
| 18 | 408687299328542444880 |
| 19 | 13389274565474007735009 |
| 20 | 457150279686453405468780 |
[0,0,1,28,570,10700,200235,3857672,77620788, 1641549000,36576771165,859032716740, 21251178078702,553095031003060,15122143306215855, 433634860865610320,13020228528050054760, 408687299328542444880,13389274565474007735009, 457150279686453405468780] |