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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 108 |
| 3 | 1368 |
| 4 | 13896 |
| 5 | 127512 |
| 6 | 1104264 |
| 7 | 9211608 |
| 8 | 74853576 |
| 9 | 596581272 |
| 10 | 4684312584 |
| 11 | 36347893848 |
| 12 | 279339197256 |
| 13 | 2129701963032 |
| 14 | 16128206816904 |
| 15 | 121439499248088 |
| 16 | 909870855444936 |
| 17 | 6787656513072792 |
| 18 | 50443519266217224 |
| 19 | 373614100586474328 |
[0,108,1368,13896,127512,1104264,9211608,74853576, 596581272,4684312584,36347893848,279339197256, 2129701963032,16128206816904,121439499248088, 909870855444936,6787656513072792, 50443519266217224,373614100586474328] |