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A069058
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Numbers n such that A017666(n)=phi(n).
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1
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1, 18, 72, 162, 648, 1152, 1458, 4608, 5832, 10368, 13122, 41472, 52488, 73728, 93312, 118098, 294912, 373248, 472392, 663552, 839808, 1062882, 2654208, 3359232, 4251528, 4718592, 5971968, 7558272, 9565938, 18874368, 23887872
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OFFSET
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1,2
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COMMENTS
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Appears to be a subset of A195321, i.e. all terms greater than 1 are of the form 18*n^2. - William J. Keith, May 25 2016
It also appears to be a subset of A003586, i.e., all the terms below 10^12 are of the form 2^i*3^j. - Giovanni Resta, May 26 2016
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LINKS
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MATHEMATICA
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Select[Range[10^6], Denominator@ Total[1/Divisors@ #] == EulerPhi@ # &] (* Michael De Vlieger, May 25 2016 *)
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PROG
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(PARI) for(n=1, 2500000, if(denominator(sumdiv(n, k, 1/k)) == eulerphi(n), print1(n, ", ")))
(PARI) isok(n) = denominator(sigma(n)/n) == eulerphi(n); \\ Michel Marcus, May 26 2016
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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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