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A246803
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Solutions of phi(sigma(x)) = x-phi(x).
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1
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6, 10, 14, 20, 22, 24, 34, 40, 44, 46, 56, 62, 68, 88, 92, 94, 106, 136, 142, 152, 164, 184, 188, 212, 214, 232, 248, 254, 284, 332, 376, 382, 384, 424, 428, 464, 472, 568, 632, 640, 668, 712, 764, 766, 856, 862, 864, 896, 944, 1004, 1016, 1172, 1192, 1294, 1408, 1424, 1432
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OFFSET
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1,1
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COMMENTS
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For n>1, 2*A005105(n) is in the sequence.
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LINKS
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EXAMPLE
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20 is in the sequence since phi(sigma(20)) = phi(42) = 12 = 20-phi(20).
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MAPLE
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MATHEMATICA
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Select[Range[1500], EulerPhi[DivisorSigma[1, #]]==#-EulerPhi[#]&]
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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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