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A127992
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Number of different prime factors of 2n^3 - 2n + 9.
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4
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1, 2, 2, 2, 2, 3, 2, 2, 3, 3, 2, 3, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 4, 2, 3, 3, 3, 3, 3, 3, 2, 4, 3, 2, 2, 3, 3, 2, 3, 2, 3, 2, 3, 4, 3, 2, 3, 2, 4, 3, 4, 3, 2, 2, 3, 2, 2, 4, 2, 3, 4, 3, 3, 3, 4, 3, 2, 2, 2, 3, 3, 4, 3, 3, 4, 3, 3, 4, 4, 2, 2, 2, 3, 3, 3, 4, 3, 4, 2, 3, 2, 2, 3, 3, 3, 2, 4, 3, 2, 3, 4, 2, 3, 2, 4
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| All numbers generated by the irreducible polynomial 2n^3 - 2n + 9 (A127979) are odd and composite. Largest prime factor A127990, number of prime factors A127992
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MATHEMATICA
| a = {}; Do[AppendTo[a, 2n^3 - 2n + 9], {n, 1, 300}]; b = {}; Do[c = FactorInteger[a[[n]]]; d = Length[c]; AppendTo[b, d], {n, 1, Length[a]}]; b (*Artur Jasinski*)
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CROSSREFS
| Cf. A127979, A127990.
Sequence in context: A033618 A061357 A138139 * A169989 A067595 A184721
Adjacent sequences: A127989 A127990 A127991 * A127993 A127994 A127995
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KEYWORD
| nonn
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AUTHOR
| Artur Jasinski (grafix(AT)csl.pl), Feb 10 2007
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