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!)
A124074 Consider the map that sends a number m to m - reverse(m) if that is nonnegative, otherwise to m + reverse(m). Sequence gives those numbers that reach a nonzero cycle under repeated application of this map. 2
119, 129, 169, 179, 188, 198, 200, 210, 218, 220, 228, 230, 240, 249, 250, 260, 268, 270, 278, 280, 287, 290, 297, 299, 300, 301, 310, 311, 317, 320, 321, 327, 330, 331, 340, 341, 348, 349, 350, 351, 360, 361, 367, 370, 371, 377, 380, 381, 386, 389, 390 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

There are values of n that apparently grow without bounds under repeated application of this map beginning with 10598, 10698, 10798, 10898, 11588, 11688, 11788, 11888, 11999, ... - Ray Chandler, Oct 10 2017

LINKS

Ray Chandler, Table of n, a(n) for n = 1..5000

EXAMPLE

119 is a member because

119 + 911 = 1030 (since the difference is negative),

1030 - 0301 = 729 (since the difference is positive),

729 + 927 = 1656,

1656 + 6561 = 8217,

8217 - 7128 = 1089,

1089 + 9801 = 10890,

10890 - 09801 = 1089, so the terms are cyclic.

MATHEMATICA

With[{nn = 400}, Select[Range@ nn, LengthWhile[NestList[If[#1 < 0, #2, #1] & @@ {#1 - #2, #1 + #2} & @@ {#, IntegerReverse@ #} &, #1, #2], # > 0 &] == #2 + 1 & @@ {#, 2^Log2@ #} &]] (* Michael De Vlieger, Oct 10 2017 *)

CROSSREFS

Cf. A001232 gives the nonzero fixed points of map.

Sequence in context: A049048 A328973 A133626 * A231372 A103154 A039557

Adjacent sequences:  A124071 A124072 A124073 * A124075 A124076 A124077

KEYWORD

base,nonn

AUTHOR

S├ębastien Dumortier, Nov 05 2006

EXTENSIONS

Definition clarified by Ray Chandler, Oct 10 2017

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 September 23 07:26 EDT 2021. Contains 347609 sequences. (Running on oeis4.)