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A325312
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Odd numbers k for which sigma(k^2) == 3 (mod 4) and sigma(k^2) > 2*k^2.
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3
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105, 315, 495, 735, 945, 1155, 1485, 1995, 2205, 2415, 2625, 2835, 2925, 3135, 3255, 3315, 3465, 3795, 4455, 4515, 4935, 5115, 5145, 5445, 5655, 5985, 6195, 6615, 6825, 7035, 7095, 7245, 7455, 7605, 7755, 7875, 8085, 8295, 8505, 8715, 8775, 8925, 9009, 9405, 9735, 9765, 9945, 10395, 10725, 10815, 11235, 11385, 11781, 12375
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OFFSET
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1,1
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COMMENTS
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Square roots of A325311, odd abundant numbers k for which sigma(k) == 3 mod 4.
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LINKS
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FORMULA
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MATHEMATICA
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Select[Range[1, 12375 , 2], Mod[(s = DivisorSigma[1, #^2]), 4] == 3 && s > 2*#^2 &] (* Amiram Eldar, Apr 05 2024 *)
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PROG
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(PARI) isA325312(n) = { my(t=sigma(n*n)); (n%2 && 3==(t%4) && t>(2*n*n)); };
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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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