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A230028 Numbers n such that phi(n) = reversal(n-20). 1
104, 824, 800024, 8000024, 84803024, 8483021444 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If p=10^m+3 is prime then 8*p is in the sequence.

84803024 is the only known term of the sequence which is not of this form.

a(7) > 10^11. - Giovanni Resta, Dec 13 2013

LINKS

Table of n, a(n) for n=1..6.

EXAMPLE

phi(104)=48=reversal(84)=reversal(104-20).

MATHEMATICA

Do[If[EulerPhi[n]==FromDigits[Reverse[IntegerDigits[n-20]]], Print[n]], {n, 21, 90000000}]

CROSSREFS

Cf. A000010, A004086.

Sequence in context: A206021 A206014 A106298 * A132434 A187589 A200196

Adjacent sequences:  A230025 A230026 A230027 * A230029 A230030 A230031

KEYWORD

nonn,base,bref,more

AUTHOR

Farideh Firoozbakht, Dec 13 2013

EXTENSIONS

a(6) from Giovanni Resta, Dec 13 2013

STATUS

approved

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Last modified February 20 06:26 EST 2019. Contains 320332 sequences. (Running on oeis4.)