A069747 Numbers n such that n and phi(n) are both palindromes.

1, 2, 3, 4, 5, 6, 7, 8, 9, 535, 767, 20502, 50805, 53035, 58085, 58585, 59395, 82428, 88188, 3269623, 5808085, 5846485, 8110118, 8666668, 8818188, 8872788, 8875788, 473040374, 515050515, 530303035, 535353535, 580303085, 580858085, 581585185, 585797585

Offset

1,2

Comments

For an arithmetical function f, call the pairs (x,y) such that y = f(x) and x, y are palindromes the "palinpairs" of f. a(n) is then the sequence of abscissae of palinpairs of f(n) = phi(n).

Links

Giovanni Resta, Table of n, a(n) for n = 1..766 (terms < 10^19)

Example

phi(58085) = 46464, so 58085 is a term of the sequence.

Mathematica

isPalin[n_] := (n == FromDigits[Reverse[IntegerDigits[n]]]); Do[m = EulerPhi[n]; If[isPalin[n] && isPalin[m], Print[{n, m}]], {n, 1, 10^6}]

Crossrefs

Sequence in context: A344822 A004893 A069282 * A308126 A124107 A257275

Adjacent sequences: A069744 A069745 A069746 * A069748 A069749 A069750

Keyword

nonn,base

Author

Joseph L. Pe, Apr 22 2002

Extensions

More terms from Jason Earls, May 07 2002

Status

approved