A230028 Numbers n such that phi(n) = reversal(n-20).

104, 824, 800024, 8000024, 84803024, 8483021444

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: A206014 A106298 A337145 * A340898 A132434 A187589

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