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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 18 |
| 3 | 198 |
| 4 | 2442 |
| 5 | 27396 |
| 6 | 322238 |
| 7 | 3676684 |
| 8 | 42682364 |
| 9 | 490330760 |
| 10 | 5667610636 |
| 11 | 65270671720 |
| 12 | 753317707256 |
| 13 | 8683177195608 |
| 14 | 100163807669976 |
| 15 | 1154904765618976 |
| 16 | 13319816385434800 |
| 17 | 153596409580655296 |
[1,18,198,2442,27396,322238,3676684,42682364, 490330760,5667610636,65270671720,753317707256, 8683177195608,100163807669976,1154904765618976, 13319816385434800,153596409580655296] |