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A173086
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Numbers n such that n, n^2 - 6, and n^2 + 6 are semiprime.
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1
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4, 10, 49, 95, 121, 217, 247, 289, 295, 301, 305, 335, 371, 427, 469, 493, 535, 551, 581, 583, 707, 721, 745, 749, 767, 815, 817, 835, 851, 893, 899, 901, 973, 1099, 1169, 1205, 1219, 1253, 1333, 1349, 1379, 1405, 1501, 1603, 1685, 1711, 1739, 1751, 1757, 1765
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OFFSET
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1,1
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LINKS
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EXAMPLE
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4=2*2, 4^2-6=10=2*5, 4^2+6=22=2*11, so 4 is in the sequence.
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MATHEMATICA
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f[n_]:=Last/@FactorInteger[n]=={1, 1}||Last/@FactorInteger[n]=={2}; lst={}; Do[If[f[n], a=n^2-6; b=n^2+6; If[f[a]&&f[b], AppendTo[lst, n]]], {n, 8!}]; lst
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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