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A070807
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Composite numbers n such that Cototient(totient(n))=A070556(n) is power of 2.
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2
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4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 26, 28, 30, 32, 34, 35, 36, 39, 40, 42, 45, 48, 51, 52, 56, 58, 60, 64, 65, 68, 70, 72, 78, 80, 84, 85, 87, 90, 96, 102, 104, 105, 112, 116, 119, 120, 128, 130, 136, 140, 144, 145, 153, 156, 160, 168, 170, 174, 180, 192
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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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n=87=3.29:phi[87]=56,56-phi[56]=56-24=32
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MATHEMATICA
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Do[s= EulerPhi[n]-EulerPhi[EulerPhi[n]]; If[IntegerQ[Log[2, s]]&&!PrimeQ[n], Print[n]], {n, 1, 10000000}]
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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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