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A112717 9-digit numbers n such that phi(n) = d_1 d_2 d_3*d_4 d_5 d_6* d_7 d_8 d_9 where d_1 d_2 ... d_9 is the decimal expansion of n. 0

%I #5 Mar 30 2012 17:37:43

%S 102873384,104754444,104840625,104963320,106600792,108512770,

%T 108860625,108864585,110640784,110756648,116660400,116672500,

%U 117480648,120297912,120876448,120916400,121864290,124704384,125792500,126528640,128333700

%N 9-digit numbers n such that phi(n) = d_1 d_2 d_3*d_4 d_5 d_6* d_7 d_8 d_9 where d_1 d_2 ... d_9 is the decimal expansion of n.

%e phi(128972250)=128*972*250, so 128972250 is in the sequence.

%t Do[h=IntegerDigits[n]; k=Length[h]; If[EulerPhi[n]==Product[ 100*h[[3j-2]]+10h[[3j-1]]+h[[3j]], {j, k/3}], Print[n]], {n, 10^8, 128400000}]

%Y Cf. A058627, A112714, A112715.

%K base,fini,nonn

%O 1,1

%A _Farideh Firoozbakht_, Sep 16 2005

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Last modified April 24 16:25 EDT 2024. Contains 371961 sequences. (Running on oeis4.)