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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 18 |
| 3 | 268 |
| 4 | 5500 |
| 5 | 143046 |
| 6 | 4491340 |
| 7 | 164927288 |
| 8 | 6926613912 |
| 9 | 327225762250 |
| 10 | 17166979868764 |
| 11 | 989951268341124 |
| 12 | 62226648527948008 |
| 13 | 4234070369464440974 |
| 14 | 310027061374942635000 |
| 15 | 24305529829528548674800 |
| 16 | 2031272969339630171158576 |
| 17 | 180267634530033586511045778 |
[1,2,18,268,5500,143046,4491340,164927288, 6926613912,327225762250,17166979868764, 989951268341124,62226648527948008, 4234070369464440974,310027061374942635000, 24305529829528548674800,2031272969339630171158576, 180267634530033586511045778] |