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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 0 |
| 4 | 1 |
| 5 | 30 |
| 6 | 180 |
| 7 | 700 |
| 8 | 3780 |
| 9 | 11844 |
| 10 | 50610 |
| 11 | 325820 |
| 12 | 5803380 |
| 13 | 126594910 |
| 14 | 2114901789 |
| 15 | 28282722650 |
| 16 | 323420067880 |
| 17 | 3190581939996 |
| 18 | 29336527986960 |
| 19 | 245438739897312 |
| 20 | 1967485926594030 |
| 21 | 16000631392009320 |
| 22 | 184418174847183508 |
| 23 | 4054670001158799616 |
| 24 | 111835386569787369559 |
[1,1,1,0,1,30,180,700,3780,11844,50610,325820, 5803380,126594910,2114901789,28282722650, 323420067880,3190581939996,29336527986960, 245438739897312,1967485926594030, 16000631392009320,184418174847183508, 4054670001158799616,111835386569787369559] |