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A257550
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Numbers n such that phi(n) = 5*phi(n+1).
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2
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17907119, 18828809, 31692569, 73421039, 179467469, 322757819, 337567229, 627702389, 975314339, 2537636009, 2722271369, 3328653509, 3917646809, 5529412349, 6369847469, 11179199849, 11201693579, 11363832479, 13442120999, 16781760449, 19751331599, 20002320029
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OFFSET
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1,1
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LINKS
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EXAMPLE
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phi(17907119) = 16588800 = 5*phi(17907120).
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MATHEMATICA
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a1={}; nmax=10^9; last=EulerPhi[1]; n=2;
While[n<nmax, ep=EulerPhi[n];
If[last==5ep, AppendTo[a1, n-1]; ];
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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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