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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 18 |
| 3 | 189 |
| 4 | 2952 |
| 5 | 63225 |
| 6 | 1759374 |
| 7 | 61261200 |
| 8 | 2595618720 |
| 9 | 130963993263 |
| 10 | 7734817065600 |
| 11 | 527276606418837 |
| 12 | 41005535326851456 |
| 13 | 3602215645092352314 |
| 14 | 354438336568129922052 |
| 15 | 38776184401330464272910 |
| 16 | 4686507224871009709115232 |
| 17 | 622194587177907979874119473 |
[1,3,18,189,2952,63225,1759374,61261200, 2595618720,130963993263,7734817065600, 527276606418837,41005535326851456, 3602215645092352314,354438336568129922052, 38776184401330464272910,4686507224871009709115232, 622194587177907979874119473] |