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A164274
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(n-th isolated prime) plus (n-th isolated composite).
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0
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6, 29, 49, 65, 83, 109, 139, 155, 191, 205, 251, 277, 311, 349, 361, 395, 413, 481, 505, 545, 599, 677, 695, 739, 815, 877, 917, 949, 979, 1013, 1169, 1189, 1201, 1237, 1265, 1409, 1429, 1451, 1471, 1531, 1595, 1679, 1735, 1757, 1781, 1807, 1919, 1951, 1985, 1997
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OFFSET
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1,1
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COMMENTS
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Isolated composites are composites surrounded by two primes, hence the average of a twin prime pair.
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LINKS
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FORMULA
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EXAMPLE
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a(1)=2+4=6. a(2)=23+6=29.
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MATHEMATICA
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With[{prs=Prime[Range[300]], nn=50}, tps=Select[Partition[prs, 2, 1], Last[#]-First[#]==2&]; iscos=Mean/@tps; isprs = Complement[prs, Flatten[tps]]; Total/@Thread[{Take[isprs, nn], Take[iscos, nn]}]] (* Harvey P. Dale, Sep 20 2011 *)
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CROSSREFS
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KEYWORD
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nonn,less
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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