login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A069747 Numbers n such that n and phi(n) are both palindromes. 3
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 (list; graph; refs; listen; history; text; internal format)
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: A307887 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 9 15:32 EDT 2020. Contains 335543 sequences. (Running on oeis4.)