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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 7 |
| 3 | 69 |
| 4 | 890 |
| 5 | 14171 |
| 6 | 268359 |
| 7 | 5889727 |
| 8 | 146974816 |
| 9 | 4109405121 |
| 10 | 127244583935 |
| 11 | 4322206448669 |
| 12 | 159794394016818 |
| 13 | 6387453554224051 |
| 14 | 274500708437617375 |
| 15 | 12620645134576175199 |
| 16 | 618137110885794967376 |
| 17 | 32130509120926762128353 |
[0,1,7,69,890,14171,268359,5889727,146974816, 4109405121,127244583935,4322206448669, 159794394016818,6387453554224051, 274500708437617375,12620645134576175199, 618137110885794967376,32130509120926762128353] |