A112717 - OEIS

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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.

102873384, 104754444, 104840625, 104963320, 106600792, 108512770, 108860625, 108864585, 110640784, 110756648, 116660400, 116672500, 117480648, 120297912, 120876448, 120916400, 121864290, 124704384, 125792500, 126528640, 128333700

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..21.

EXAMPLE

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

MATHEMATICA

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}]

CROSSREFS

Cf. A058627, A112714, A112715.

Sequence in context: A235161 A235724 A241792 * A114679 A157859 A157863

Adjacent sequences: A112714 A112715 A112716 * A112718 A112719 A112720

KEYWORD

base,fini,nonn

AUTHOR

Farideh Firoozbakht, Sep 16 2005

STATUS

approved