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Search: id:A098216
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| A098216 |
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Nonprime numbers n for which cototient[n]=n-phi[n] is a decimal repdigit. |
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+0
4
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| 1, 4, 6, 8, 9, 10, 12, 14, 15, 16, 21, 25, 27, 30, 35, 49, 60, 86, 90, 93, 120, 121, 145, 159, 172, 175, 195, 231, 245, 253, 279, 291, 327, 365, 497, 535, 559, 693, 703, 737, 886, 979, 981, 993, 1037, 1111, 1121, 1411, 1457, 1517, 1617, 1772, 1774, 2047, 2059
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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n=97002, n-phi[n]=66666
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MATHEMATICA
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ta={{0}}; Do[s=Length[Union[IntegerDigits[n-EulerPhi[n]]]]; If[Equal[s, 1]&&!PrimeQ[n], Print[{n, n-EulerPhi[n]}]; ta=Append[ta, n]], {n, 1, 100000}]; ta=Delete[ta, 1]; ta-EulerPhi[ta]
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CROSSREFS
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Cf. A096503, A010785.
Sequence in context: A050655 A117098 A077136 this_sequence A063806 A063989 A117097
Adjacent sequences: A098213 A098214 A098215 this_sequence A098217 A098218 A098219
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KEYWORD
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nonn,base
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Oct 22 2004
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