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URL: https://oeis.org/A165012

⇱ A165012 - OEIS

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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).
31
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
OFFSET
0,5
LINKS
Indranil Ghosh, Table of n, a(n) for n = 0..16384 (terms 0..1024 from Joseph Myers)
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
KEYWORD
base,nonn
AUTHOR
Joseph Myers, Sep 04 2009
STATUS
approved