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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 6 |
| 4 | 45 |
| 5 | 415 |
| 6 | 4693 |
| 7 | 65010 |
| 8 | 1073640 |
| 9 | 20669837 |
| 10 | 454793822 |
| 11 | 11259684418 |
| 12 | 309761863916 |
| 13 | 9373389023182 |
| 14 | 309374515194621 |
| 15 | 11059527891811334 |
| 16 | 425655578031419604 |
| 17 | 17547665070746310736 |
| 18 | 771403345825446116583 |
| 19 | 36020103485009885093324 |
[0,2,6,45,415,4693,65010,1073640,20669837, 454793822,11259684418,309761863916,9373389023182, 309374515194621,11059527891811334, 425655578031419604,17547665070746310736, 771403345825446116583,36020103485009885093324] |