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A015734
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Odd numbers k such that d(k) does not divide phi(k).
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2
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25, 27, 75, 81, 121, 189, 225, 275, 289, 297, 343, 363, 405, 425, 513, 529, 567, 575, 605, 621, 725, 729, 825, 837, 841, 867, 1025, 1029, 1053, 1089, 1161, 1175, 1225, 1269, 1275, 1325, 1331, 1377, 1445, 1475, 1539, 1587, 1593, 1681, 1725
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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Select[Range[1, 2000, 2], !Divisible[EulerPhi[#], DivisorSigma[0, #]] &] (* Amiram Eldar, May 15 2024 *)
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PROG
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(PARI) is(k) = if(k%2, my(f = factor(k), d = numdiv(f), p = eulerphi(f)); p % d, 0); \\ Amiram Eldar, May 15 2024
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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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