Question 419106
2n^2 gives 
2,8,18,32,50,72, . . . .
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However, 
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n^5-15n^4+85n^3-223n^2+274n-120 gives
2,8,18,32,50,192, . . . .
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But then there is,
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(2/5)n^5-6n^4+34n^3-88n^2+(548/5)n-48 that gives
2,8,18,32,50,120, . . . .
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And then there is ....
... I can keep going all day, but I'll just stop there.
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All these work, take your pick :)
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Finally, the point also is that given any finite set of numbers, the set does not necessarily define any single sequence.