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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 19 |
| 2 | 342 |
| 3 | 6156 |
| 4 | 110808 |
| 5 | 1994544 |
| 6 | 35901792 |
| 7 | 646232256 |
| 8 | 11632180608 |
| 9 | 209379250944 |
| 10 | 3768826516992 |
| 11 | 67838877305856 |
| 12 | 1221099791505408 |
| 13 | 21979796247097344 |
| 14 | 395636332447752192 |
| 15 | 7121453984059539456 |
[1,19,342,6156,110808,1994544,35901792,646232256, 11632180608,209379250944,3768826516992, 67838877305856,1221099791505408,21979796247097344, 395636332447752192,7121453984059539456] |