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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 18 |
| 3 | 369 |
| 4 | 1674 |
| 5 | 31428 |
| 6 | 266733 |
| 7 | 3012714 |
| 8 | 19924299 |
| 9 | 319970007 |
| 10 | 2688208641 |
| 11 | 27248985549 |
| 12 | 248061612240 |
| 13 | 2597556114648 |
| 14 | 25367004717831 |
| 15 | 289880288735373 |
| 16 | 2289952155529719 |
| 17 | 23895509092285545 |
| 18 | 252143223166599723 |
| 19 | 2308267172943599733 |
| 20 | 22389894059315522040 |
[1,3,18,369,1674,31428,266733,3012714,19924299, 319970007,2688208641,27248985549,248061612240, 2597556114648,25367004717831,289880288735373, 2289952155529719,23895509092285545, 252143223166599723,2308267172943599733, 22389894059315522040] |