A165071 - OEIS

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A165071

a(n) = image of n under the base-7 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order)

0, 0, 0, 0, 0, 0, 0, 6, 0, 6, 12, 18, 24, 30, 12, 6, 0, 6, 12, 18, 24, 18, 12, 6, 0, 6, 12, 18, 24, 18, 12, 6, 0, 6, 12, 30, 24, 18, 12, 6, 0, 6, 36, 30, 24, 18, 12, 6, 0, 48, 48, 96, 144, 192, 240, 288, 48, 0, 48, 96, 144, 192, 240, 96, 48, 48, 96, 144, 192, 240, 144, 96, 96, 96

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,8

LINKS

Indranil Ghosh, Table of n, a(n) for n = 0..16807 (terms 0..2401 from Joseph Myers)

Index entries for the Kaprekar map

EXAMPLE

For n = 11, 11_10 = 14_7. So, a(11) = 41_7 - 14_7 = 29 - 11 = 18. - Indranil Ghosh, Feb 02 2017

MATHEMATICA

a[n_] := With[{dd = IntegerDigits[n, 7]}, FromDigits[ReverseSort[dd], 7] - FromDigits[Sort[dd], 7]];

a /@ Range[0, 100] (* Jean-François Alcover, Jan 08 2020 *)

CROSSREFS

Cf. A165072.

In other bases: A164884 (base 2), A164993 (base 3), A165012 (base 4), A165032 (base 5), A165051 (base 6), A165090 (base 8), A165110 (base 9), A151949 (base 10).

Sequence in context: A141462 A354330 A055955 * A341483 A223033 A237444

Adjacent sequences: A165068 A165069 A165070 * A165072 A165073 A165074

KEYWORD

base,nonn

AUTHOR

Joseph Myers, Sep 04 2009

STATUS

approved