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A151962
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Length of preperiodic part of trajectory of n under iteration of the Kaprekar map in A151949.
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10
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0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 6, 4, 5, 3, 3, 5, 4, 6, 2, 1, 2, 6, 4, 5, 3, 3, 5, 4, 6, 2, 1, 2, 6, 4, 5, 3, 3, 5, 4, 6, 2, 1, 2, 6, 4, 5, 3, 3, 5, 4, 6, 2, 1, 2, 6, 4, 5, 3, 3, 5, 4, 6, 2, 1, 2, 6, 4, 5, 3, 3, 5, 4, 6, 2, 1, 2, 6, 4, 5, 3, 3, 5, 4, 6, 2, 1, 2, 6, 4, 5, 3, 3, 5, 4, 6, 2
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history;
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internal format)
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OFFSET
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0,11
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LINKS
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Joseph Myers, Table of n, a(n) for n=0..1000
Index entries for the Kaprekar map
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EXAMPLE
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13->18->63->27->45->9->0->0, so a(13)=6.
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MAPLE
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Maple program from R. J. Mathar, Aug 20 2009
A151949 := proc(n)
local tup;
tup := sort(convert(n, base, 10)) ;
add( (op(i, tup)-op(-i, tup)) *10^(i-1), i=1..nops(tup)) :
end:
A151962 := proc(n)
local tra, x ;
tra := [n] ;
x := n ;
while true do
x := A151949(x) ;
if member(x, tra, 'l') then
RETURN(l-1) ;
fi;
tra := [op(tra), x] :
od:
end:
seq(A151962(n), n=0..120) ;
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CROSSREFS
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Cf. A151949, A151963. Strictly different from A072137.
In other bases: A164885 (base 2), A164995 (base 3), A165014 (base 4), A165034 (base 5), A165053 (base 6), A165073 (base 7), A165092 (base 8), A165112 (base 9). [From Joseph Myers, Sep 05 2009]
Sequence in context: A174959 A126093 A065279 * A072137 A061569 A140835
Adjacent sequences: A151959 A151960 A151961 * A151963 A151964 A151965
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KEYWORD
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nonn,base
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AUTHOR
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N. J. A. Sloane, Aug 19 2009
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EXTENSIONS
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More terms from R. J. Mathar, Aug 20 2009
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STATUS
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approved
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