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

Author

Joseph L. Pe, Apr 22 2002

Keywords

• nonn
• base

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).

Examples

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

Links

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

Programs

Mathematica

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

Extensions

More terms from Jason Earls, May 07 2002