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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 13 |
| 5 | 12 |
| 6 | 324 |
| 7 | 1352 |
| 8 | 18368 |
| 9 | 19152 |
| 10 | 1994322 |
| 11 | 8810748 |
| 12 | 193690826 |
| 13 | 829046868 |
| 14 | 34563283272 |
| 15 | 274895151856 |
| 16 | 14554448767872 |
| 17 | 8178592487376 |
| 18 | 2493850026398472 |
| 19 | 33842416675133248 |
| 20 | 1037660717168380800 |
| 21 | 6072370562498569056 |
| 22 | 682597834324732589120 |
| 23 | 5390950170768906240000 |
[1,0,1,1,13,12,324,1352,18368,19152,1994322, 8810748,193690826,829046868,34563283272, 274895151856,14554448767872,8178592487376, 2493850026398472,33842416675133248, 1037660717168380800,6072370562498569056, 682597834324732589120,5390950170768906240000] |