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A068402
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Numbers n such that sigma(n+1)=n+phi(n).
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0
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4, 6, 32, 38, 54, 56, 84, 278, 2664, 10944, 15608, 20720, 84800, 179576, 209664, 6251904, 85505600, 125226624, 584003328, 19018936320, 20534891040, 79185129984, 87065548800, 191904215040, 964494300024
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OFFSET
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1,1
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COMMENTS
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Are there any odd values in the sequence?
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LINKS
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MATHEMATICA
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Select[Range[10^5], DivisorSigma[1, # + 1] == # + EulerPhi[#] &] (* Alonso del Arte, Feb 29 2012 *)
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PROG
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(PARI) : for(n=1, 500000, if(sigma(n+1)-n==eulerphi(n), print1(n, ", ")))
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CROSSREFS
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KEYWORD
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easy,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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