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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 3 |
| 4 | 66 |
| 5 | 1380 |
| 6 | 31460 |
| 7 | 800625 |
| 8 | 22758918 |
| 9 | 718821852 |
| 10 | 25057509036 |
| 11 | 957657379437 |
| 12 | 39878893266795 |
| 13 | 1799220308202603 |
| 14 | 87502582432459584 |
| 15 | 4566246347310609247 |
| 16 | 254625879822078742956 |
| 17 | 15115640124974801925030 |
| 18 | 952050565540607423524658 |
| 19 | 63425827673509972464868323 |
[0,0,0,3,66,1380,31460,800625,22758918,718821852, 25057509036,957657379437,39878893266795, 1799220308202603,87502582432459584, 4566246347310609247,254625879822078742956, 15115640124974801925030,952050565540607423524658, 63425827673509972464868323] |