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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 69 |
| 4 | 1230 |
| 5 | 30663 |
| 6 | 1005692 |
| 7 | 41571127 |
| 8 | 2099861244 |
| 9 | 126607647073 |
| 10 | 8945129371976 |
| 11 | 729628409684925 |
| 12 | 67868881258920424 |
| 13 | 7125522244948969319 |
| 14 | 837004398237510194704 |
| 15 | 109173596976047915341823 |
| 16 | 15708090522743045757716496 |
| 17 | 2478722722731315203268137729 |
[1,1,6,69,1230,30663,1005692,41571127,2099861244, 126607647073,8945129371976,729628409684925, 67868881258920424,7125522244948969319, 837004398237510194704,109173596976047915341823, 15708090522743045757716496, 2478722722731315203268137729] |