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%I #5 Mar 30 2012 17:28:42
%S 0,0,6174,62964,420876,7509843,64308654,864197532,6431088654,
%T 86420987532,643310886654,8643209876532,43333208766666,
%U 885432098765412,6543331088666544,88754320987654212,643111110888888654
%N Iterate the Kaprekar map of A151949 starting at the n-digit number 100...01; sequence gives the lowest number in the resulting cycle.
%H Joseph Myers, <a href="/A151967/b151967.txt">Table of n, a(n) for n=2..1000</a> [From _Joseph Myers_, Aug 21 2009]
%H <a href="/index/K#Kaprekar_map">Index entries for the Kaprekar map</a>
%e a(6) = 420876: 100001 -> 109989 -> 980811 -> 976221 -> 853542 -> 620874 -> 851742 -> 750843 -> 840852 -> 860832 -> 862632 -> 642654 -> 420876 -> 851742 -> ..., a cycle of length 7 with smallest member 420876.
%t (Mma program from Harvey P. Dale) To find the first 20 terms of the trajectory of 10001, for instance:
%t f[n_]:=Module[{idn=IntegerDigits[n],idns},idns=Sort[idn];Abs[FromDigits[ idns]-FromDigits[Reverse[idns]]]]
%t NestList[f,10001,20]
%Y See A151968 for the length of the cycles. Cf. A151957, A151958.
%Y Different from A151957.
%K nonn,base
%O 2,3
%A _N. J. A. Sloane_, Aug 20 2009
%E Extended by _Joseph Myers_, Aug 21 2009
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