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A066134
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Numbers from A066112 that are neither square nor twice a square, i.e., are not in A028982 but are in A028983.
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1
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48, 180, 245, 432, 500, 605, 931, 980, 1200, 1280, 1620, 1805, 2205, 2352, 2420, 3380, 3724, 3888, 3920, 4500, 4655, 5445, 5780, 5808, 6125, 6845, 7203, 7220, 7936, 8112, 8379, 8405, 8820, 9072, 9251, 9680, 10580, 10800, 11520, 11760, 12500
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listen;
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text;
internal format)
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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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180 is neither square nor 2*square, but sigma_4(180)/sigma_2(180) = 1135275414/49686 = 22849 = 73*313.
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PROG
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(PARI) { n=0; for (m=1, 10^9, if (issquare(m) || issquare(m/2), next); if (frac(f=sigma(m, 4)/sigma(m, 2)), next); if (!isprime(f), write("b066134.txt", n++, " ", m); if (n==1000, return)) ) } \\ Harry J. Smith, Feb 02 2010
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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