A165012 - OEIS

A165012

a(n) = image of n under the base-4 Kaprekar map n -> (n with digits sorted into descending order) - (n with digits sorted into ascending order).

0, 0, 0, 0, 3, 0, 3, 6, 6, 3, 0, 3, 9, 6, 3, 0, 15, 15, 30, 45, 15, 0, 15, 30, 30, 15, 15, 30, 45, 30, 30, 30, 30, 30, 30, 45, 30, 15, 15, 30, 30, 15, 0, 15, 45, 30, 15, 15, 45, 45, 45, 45, 45, 30, 30, 30, 45, 30, 15, 15, 45, 30, 15, 0, 63, 75, 138, 201, 75, 63, 126, 189, 138, 126

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

OFFSET

0,5

LINKS

Indranil Ghosh, Table of n, a(n) for n = 0..16384 (terms 0..1024 from Joseph Myers)

Index entries for the Kaprekar map

EXAMPLE

For n = 11, 11_10 = 23_4. So, a(11) = 32_4 - 23_4 = 14 - 11 = 3. - Indranil Ghosh, Feb 02 2017

MATHEMATICA

b4km[n_]:=Module[{idn4=Sort[IntegerDigits[n, 4]]}, FromDigits[ Reverse[ idn4], 4]-FromDigits[idn4, 4]]; Array[b4km, 80, 0]

PROG

(PARI) cons(m) = {local(b, r); r=0; b=1; for(i=1, matsize(m)[2], r=r+b*m[i]; b=b*4); r}

A165012(n) = {local(m, r); r=[]; m=n; while(m>0, r=concat(m%4, r); m=floor(m/4)); cons(vecsort(r, , 0))-cons(vecsort(r, , 4))} \\ Michael B. Porter, Nov 05 2009

CROSSREFS

Cf. A165013.

In other bases: A164884 (base 2), A164993 (base 3), A165032 (base 5), A165051 (base 6), A165071 (base 7), A165090 (base 8), A165110 (base 9), A151949 (base 10).

Sequence in context: A226568 A038517 A055949 * A198126 A074694 A127803

Adjacent sequences: A165009 A165010 A165011 * A165013 A165014 A165015

KEYWORD

base,nonn

AUTHOR

Joseph Myers, Sep 04 2009

STATUS

approved