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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 55 |
| 3 | 602 |
| 4 | 7263 |
| 5 | 93192 |
| 6 | 1247636 |
| 7 | 17230290 |
| 8 | 243669007 |
| 9 | 3511010950 |
| 10 | 51361157967 |
| 11 | 760784343128 |
| 12 | 11387857096900 |
| 13 | 171988619895216 |
| 14 | 2617571721008520 |
| 15 | 40105744064042626 |
| 16 | 618116513218831407 |
| 17 | 9576289414539654450 |
| 18 | 149053521972041737413 |
[1,6,55,602,7263,93192,1247636,17230290,243669007, 3511010950,51361157967,760784343128, 11387857096900,171988619895216,2617571721008520, 40105744064042626,618116513218831407, 9576289414539654450,149053521972041737413] |