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Search: id:A112009
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| A112009 |
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Numbers n with even length such that phi(n)=d_1^d_2*d_3^d_4*...* d_(k-1)^d_k where d_1 d_2 ... d_k is the decimal expansion of n. |
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+0
4
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| 113724, 116680, 126620, 176453, 236520, 12146841, 12514635, 13334445, 13469331, 13813728, 16473510, 18259344, 20116537, 20119347, 21324832, 23336066, 27923616
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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There is no further term up to 3*10^7.
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EXAMPLE
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27923616 is in the sequence because phi(27923616)=2^7*9^2*3^6*1^6.
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MATHEMATICA
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Do[h = IntegerDigits[n]; k = Length[h]; If[EvenQ[k] && Select[ Range[k/2], h[[2#-1]] == 0 &] == {} && EulerPhi[n]==Product[ h[[2j-1]]^h[[2j]], {j, k/2}], Print[n]], {n, 30000000}]
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CROSSREFS
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Cf. A110084, A112010, A112011.
Sequence in context: A066790 A135411 A108387 this_sequence A034633 A138266 A023092
Adjacent sequences: A112006 A112007 A112008 this_sequence A112010 A112011 A112012
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KEYWORD
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base,more,nonn
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AUTHOR
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Farideh Firoozbakht (f.firoozbakht(AT)math.ui.ac.ir), Aug 26 2005
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